ASVAB STUDY GUIDES

Absolutely. I’d not try to read all 270 pages tonight. The goal is to know the big idea behind every topic and memorize the formulas/rules that can actually save you points.

The guide covers Arithmetic Reasoning, Assembling Objects, Auto & Shop, Electronics, General Science, Mathematics Knowledge, Mechanical Comprehension, Paragraph Comprehension, and Word Knowledge.

🚨 ASVAB 10-HOUR CRAM GUIDE

1. ARITHMETIC REASONING — WORD PROBLEMS

Main idea: Turn words into math.

🔑 Know these words

sum = addition
difference = subtraction
product = multiplication
quotient = division
per = divide/rate
of = usually multiply
percent = ÷ 100
increase = add
decrease = subtract
twice = ×2
half = ÷2

Ratios

A ratio compares things.

2:3 means 2 for every 3.

If the ratio stays the same:
2:3 = 6:9

Rates

The big formula:

Distance = Rate × Time

So:

D = RT
R = D/T
T = D/R

Percent

Percent = Part ÷ Whole × 100

Example: 20 is what percent of 80?

20 ÷ 80 × 100 = 25%

Percent change

Change ÷ Original × 100

Work problems

If someone completes a job in 2 hours:

rate = 1/2 job per hour

If another takes 4 hours:

rate = 1/4

Together:

1/2 + 1/4 = 3/4 job/hour

Then:

1 ÷ 3/4 = 4/3 hours

Probability

Probability = favorable outcomes ÷ total possible outcomes

If there are 4 possibilities and 1 is favorable:

1/4 = 25%

Sequences

Look for the pattern:

+3 each time → arithmetic
×2 each time → geometric
changing pattern → look at differences between numbers

2. BASIC MATH YOU NEED

Number Types

Whole: 0, 1, 2, 3...
Integer: positive, negative, and zero
Rational: can be written as a fraction
Irrational: cannot be written as a fraction
Prime: only factors are 1 and itself
Composite: has more than two factors

Factors vs. Multiples

Factor: goes INTO a number.

Factors of 12:
1, 2, 3, 4, 6, 12

Multiple: what you get by multiplying.

Multiples of 12:
12, 24, 36, 48...

GCF

Greatest Common Factor = biggest factor shared by two numbers.

LCM

Least Common Multiple = smallest multiple shared by two numbers.

3. FRACTIONS

Add/subtract

Same denominator first.

1/4 + 2/4 = 3/4

Different denominators → find the LCM.

Multiply

Straight across:

a/b × c/d = ac/bd

Divide

Keep → Change → Flip

a/b ÷ c/d = a/b × d/c

Mixed → improper

Multiply whole number × denominator, then add numerator.

2 1/3 = 7/3

Decimal

Tenths = 0.1
Hundredths = 0.01
Thousandths = 0.001

Fraction → percent

numerator ÷ denominator × 100

4. EXPONENTS / RADICALS

Exponents

2³ = 2 × 2 × 2 = 8

Multiplying same base

Add exponents

x² × x³ = x⁵

Dividing same base

Subtract exponents

x⁵ ÷ x² = x³

Power raised to power

Multiply exponents

(x²)³ = x⁶

Negative exponent

Flip it:

x⁻² = 1/x²

Square roots

Think:

"What number multiplied by itself gives this?"

√25 = 5

Scientific notation

Number between 1 and 10 × power of 10.

4,500 = 4.5 × 10³

5. MEASUREMENT / GEOMETRY

US measurements

Memorize:

1 foot = 12 inches
1 yard = 3 feet
1 mile = 5,280 feet
1 gallon = 4 quarts
1 quart = 2 pints
1 pint = 2 cups
1 pound = 16 ounces
1 ton = 2,000 pounds

Metric

kilo = ×1000
centi = ×0.01
milli = ×0.001

Geometry

Rectangle area:
A = length × width

Triangle:
A = 1/2bh

Circle:
A = πr²

Circumference:
C = πd

Rectangular volume:
V = lwh

Sphere volume:
V = 4/3πr³

Pythagorean theorem

a² + b² = c²

Only use it for a right triangle.

6. DATA

Mean / Average

Add everything ÷ number of things

Median

Put numbers in order → middle number.

If there are two middle numbers → average them.

Mode

Most common number.

Range

Highest − lowest

Outlier

A number far away from the rest.

Probability

Again:

favorable ÷ total

7. ASSEMBLING OBJECTS

This is basically 3D visualization.

Connection questions

Match the labeled connection points.

CRITICAL:
You can rotate pieces.

You cannot mirror/flip them.

Puzzle questions

Make sure:

Every piece is present.
No extra pieces appear.
Shapes are the same.
Pieces can rotate.
Pieces cannot be flipped.

Best strategy

Don't stare at the entire thing.

Pick one weird piece or dot and see which answers have it correctly.

This section measures your ability to mentally fit objects together.

8. AUTO & SHOP

This is a BIG section in the guide, so focus on the purpose of parts, not every tiny detail.

🚗 Engine

Four-stroke cycle

INTAKE → COMPRESSION → POWER → EXHAUST

Memorize this.

Intake: air/fuel enters
Compression: piston moves up and compresses it
Power: fuel burns → pushes piston down
Exhaust: burned gases leave

Important engine parts

Piston

Moves up/down
Compresses mixture
Receives force from combustion

Connecting rod

Connects piston → crankshaft

Crankshaft

Converts up/down piston movement → rotation

Camshaft

Controls opening/closing of valves

Intake valve

Lets air/fuel in

Exhaust valve

Lets exhaust out

Cylinder

Where piston moves and combustion occurs

Cylinder head

Covers top of cylinder

Engine block

Main structure containing cylinders/passages

Gas vs diesel

Gasoline: spark ignites fuel.

Diesel: compression creates enough heat to ignite fuel.

9. ENGINE SYSTEMS

Cooling

Purpose: prevent overheating

Water pump: moves coolant
Radiator: releases heat
Thermostat: controls coolant flow
Hoses: move coolant
Radiator cap: controls pressure

Lubrication

Purpose: reduce friction, heat, and wear

Oil pan → holds oil
Oil pump → moves oil
Oil filter → removes contaminants
Oil passages → distribute oil

Fuel system

Purpose: get the correct fuel to the engine

Carburetor: older mechanical fuel/air mixing

Fuel injection: electronically controls fuel delivery

Ignition

Purpose: ignite fuel-air mixture

Battery → ignition system → high voltage → spark plug → combustion.

Electrical system

Know the basic purposes:

Battery: stores/supplies electrical energy
Alternator: charges battery while engine runs
Starter: turns engine over
Lights: electrical output
Computer: controls/monitors systems

10. DRIVETRAIN / BRAKES

Transmission

Changes how engine power is delivered to wheels.

Automatic: changes gears automatically.

Manual: driver controls gears with clutch/shifter.

Drive types

FWD: front wheels powered

RWD: rear wheels powered

AWD: all wheels can receive power automatically

4WD: all wheels powered through a dedicated system, generally for more demanding conditions.

Brakes

Know:
pedal → master cylinder → brake fluid → brakes

ABS

Anti-lock Braking System

Prevents wheels from locking during hard braking, helping maintain steering control.

11. SHOP TOOLS

Don't memorize every description. Memorize what each tool does.

Measuring

Tape measure: length
Ruler: length
Caliper: precise dimensions
Micrometer: extremely precise measurement
Level: determines horizontal/vertical level
Square: checks right angles

Striking

Claw hammer: nails/general work
Ball-peen: metalworking
Mallet: softer striking
Sledgehammer: heavy striking
Chisel: cuts material when struck

Turning

Screwdriver: screws
Wrench: bolts/nuts
Socket: bolts/nuts with ratchet

Gripping

Pliers: grip/hold/cut
Clamp: holds objects
Vise: holds work securely

Cutting

Hand saw: manual cutting
Power saw: powered cutting
Drill: makes holes
Drill bit: cutting tool that creates hole

Welding

Know the big types:

Oxyacetylene
Electric arc
Stick
MIG

And remember: welding = heat joins metal.

12. ELECTRONICS

The BIG 4

Voltage

Electrical pressure

Measured in volts (V).

Current

Flow of electric charge

Measured in amps (A).

Resistance

Opposition to current

Measured in ohms (Ω).

Power

How quickly electrical energy is used.

Measured in watts (W).

13. OHM'S LAW ⭐

This is VERY important.

V = IR

Where:

V = voltage
I = current
R = resistance

Therefore:

I = V/R

R = V/I

Example:

12V ÷ 4Ω = 3 amps

Electrical power

P = VI

So:

12V × 3A = 36 watts

14. CIRCUITS

Closed circuit

Complete path → current flows.

Open circuit

Broken path → current does not flow.

Series

One path.

If one component breaks, the whole circuit is affected.

Parallel

Multiple paths.

One branch can fail while others continue.

Conductor

Allows electricity to flow easily.

Example: copper

Insulator

Resists electricity.

Example: rubber

Semiconductor

Between conductor and insulator.

15. ELECTRONICS COMPONENTS

Resistor

Limits current.

Capacitor

Stores electrical charge.

Diode

Allows current primarily in one direction.

Transistor

Controls/amplifies electrical signals.

Fuse

Protects circuit by breaking when current gets too high.

Circuit breaker

Similar protection, but can generally be reset.

AC vs DC

AC: current changes direction.

DC: current flows in one direction.

16. GENERAL SCIENCE — BIOLOGY

Nutrition

Macronutrients

Need large amounts:

Carbohydrates
Proteins
Fats

Micronutrients

Need smaller amounts:

Vitamins
Minerals

Proteins

Build/repair tissues.

Carbohydrates

Major energy source.

Fats

Energy storage, insulation, cell functions.

17. HUMAN BODY

Skeleton

Provides:

Support
Protection
Structure

Muscles

Create movement.

Respiratory system

Gets oxygen in and removes carbon dioxide.

Circulatory system

Heart pumps blood throughout body.

Digestive system

Breaks food down → absorbs nutrients → removes waste.

Nervous system

Controls communication and responses.

Reproduction

Produces offspring.

18. CELLS

Prokaryote

No membrane-bound nucleus
Simple
Example: bacteria

Eukaryote

Has nucleus
More complex
Humans = eukaryotes

Organelles

Nucleus: controls cell/genetic information

Mitochondria: produces usable energy/ATP

Ribosomes: make proteins

Cell membrane: controls what enters/leaves

Chloroplast: photosynthesis in plants

Cell wall: support/protection in plants

Golgi: packages/ships materials

Cellular respiration

Glucose → ATP

ATP = usable cellular energy.

19. GENETICS

DNA

Stores genetic information.

Chromosome

DNA packaged into structures.

Gene

A section of DNA containing genetic information.

Haploid

One set of chromosomes.

Diploid

Two sets.

Humans:
46 chromosomes = 23 pairs

Mitosis

Produces 2 genetically identical cells.

Used for growth/repair.

Meiosis

Produces 4 cells with half the chromosomes.

Used to produce sex cells.

20. ECOLOGY

Know this hierarchy:

Biosphere → Biome → Ecosystem → Community → Population

Producers

Make their own food.

Example: plants.

Consumers

Get energy by eating organisms.

Decomposers

Break down dead material.

Food web

Shows how energy moves through an ecosystem.

Taxonomy

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

Mnemonic:

King Philip Came Over For Good Soup

21. EARTH SCIENCE

Earth's layers

Crust → Mantle → Outer Core → Inner Core

Plate tectonics

Earth's crust/lithosphere is divided into moving plates.

Plate movement causes:

Earthquakes
Volcanoes
Mountains

Rocks

Igneous: cooled magma/lava

Sedimentary: sediments compressed/cemented

Metamorphic: existing rock changed by heat/pressure

22. WEATHER

Weather vs climate

Weather: current/short-term conditions.

Climate: long-term patterns.

Air pressure

Higher pressure generally = sinking air.

Lower pressure generally = rising air.

Fronts

Where different air masses meet.

Clouds

Know the basic idea:
Clouds form when moist air cools and water vapor condenses.

23. ASTRONOMY

Know the basic solar system order:

Mercury → Venus → Earth → Mars → Jupiter → Saturn → Uranus → Neptune

Gravity

Keeps planets in orbit.

Earth's position relative to the Sun affects:

Seasons
Day/night
Amount of sunlight received

24. PHYSICS

Mass vs weight

Mass: amount of matter.

Weight: force of gravity acting on mass.

Motion

Speed tells you how fast something moves.

Speed = Distance / Time

Force

F = ma

Force = mass × acceleration.

Newton's Laws

1st: Objects keep their motion unless acted upon by a force.

2nd: More force → more acceleration.

F = ma

3rd: Every action has an equal and opposite reaction.

25. ENERGY

Kinetic energy

Energy of motion.

Potential energy

Stored energy.

Work

Work = Force × Distance

Power

How quickly work is done.

Other energy

Chemical
Electrical
Nuclear
Solar
Thermal

26. HEAT / THERMODYNAMICS

Heat transfer

Conduction: direct contact.

Convection: movement of fluids/gases.

Radiation: energy through electromagnetic waves.

Key idea

Heat moves from hot → cold.

27. CHEMISTRY

Atom

Proton: positive

Neutron: neutral

Electron: negative

Periodic table

Groups: columns
Periods: rows

Elements in the same group often have similar properties.

Compound

Two or more different elements chemically combined.

28. ACIDS & BASES

pH

Below 7: acidic
7: neutral
Above 7: basic

Important

The farther from 7, the stronger the acidity/basicity.

Neutralization

Acid + base → salt + water

29. PHYSICAL VS CHEMICAL CHANGE

Physical change

Substance remains the same.

Examples:

Melting
Freezing
Cutting
Boiling

Chemical change

New substance forms.

Examples:

Burning
Rusting
Many chemical reactions

30. MATHEMATICS KNOWLEDGE

This is more pure math than Arithmetic Reasoning.

Algebra

Combining like terms

3x + 5x = 8x

But:

3x + 5y

cannot combine.

Distributive property

3(x + 4) = 3x + 12

FOIL

For two binomials:

First → Outer → Inner → Last

(x+2)(x+3)

= x² + 3x + 2x + 6

= x² + 5x + 6

31. SOLVING EQUATIONS

Goal: get the variable alone.

Example:

2x + 6 = 14

Subtract 6:

2x = 8

Divide by 2:

x = 4

Golden rule

Whatever you do to one side, do to the other.

32. QUADRATICS ⭐

General form:

ax² + bx + c = 0

Factoring

Find two numbers that:

multiply to c
add to b

Example:

x² + 5x + 6

Numbers = 2 and 3.

(x+2)(x+3)=0

So:

x = -2 or -3

Quadratic formula

x = (-b ± √(b² − 4ac)) / 2a

Memorize this if you're comfortable with it.

33. INEQUALITIES

Same basic solving process as equations.

HUGE RULE:

If you multiply/divide by a negative, flip the inequality.

-2x > 8

Divide by -2:

x < -4

34. SYSTEMS OF EQUATIONS

Two equations → find the values that satisfy both.

Substitution

Solve one equation for a variable → plug it into the other.

Elimination

Add/subtract equations to eliminate a variable.

35. GEOMETRY

Angles

Acute = less than 90°
Right = 90°
Obtuse = 90°–180°
Straight = 180°

Triangle

Angles always add to:

180°

Quadrilateral

Interior angles add to:

360°

Pythagorean theorem

a² + b² = c²

36. CIRCLES

Diameter

Across the circle through the center.

Radius

Center → edge.

Diameter = 2 × radius

Circumference

C = 2πr

Area

A = πr²

37. COORDINATE GEOMETRY

Slope

m = (y₂ − y₁)/(x₂ − x₁)

Think:

rise ÷ run

Slope-intercept

y = mx + b

m = slope
b = y-intercept

Distance

For coordinate points, use the distance formula:

√[(x₂−x₁)² + (y₂−y₁)²]

38. MECHANICAL COMPREHENSION ⭐

Think about force, motion, and machines.

Mass

Amount of matter.

Force

Push or pull.

Gravity

Pulls objects toward each other.

Friction

Opposes motion.

Compression

Forces pushing together.

Tension

Forces pulling apart.

39. NEWTON'S LAWS

Same laws from science, but now apply them to machines.

1st

Objects resist changes in motion.

2nd

F = ma

3rd

Equal and opposite reaction.

40. TORQUE

Torque = turning force.

Think about a wrench.

Longer wrench → more torque with the same force.

41. WORK / ENERGY / POWER

Work

W = Force × Distance

Kinetic energy

Motion.

Potential energy

Stored energy.

Power

How quickly work is performed.

42. SIMPLE MACHINES ⭐

Know what each does.

Lever

Uses a pivot/fulcrum to multiply force.

Pulley

Changes direction of force and can provide mechanical advantage.

Inclined plane

Ramp → makes lifting easier by increasing distance.

Wheel & axle

Makes movement/turning easier.

Screw

Basically an inclined plane wrapped around a cylinder.

Wedge

Used to split/cut/separate.

Gears

Transfer rotational motion.

Small gear driving big gear → more torque, less speed.

Big gear driving small gear → more speed, less torque.

43. MECHANICAL ADVANTAGE

Mechanical advantage means a machine lets you get more output force from less input force.

Simple idea:

More mechanical advantage = less force required, but usually more distance/time.

Think:

Long lever
Multiple pulley sections
Gears

44. MATERIALS

Heat conduction

How easily material transfers heat.

Metal = good conductor

Plastic = poor conductor

Flexibility

Ability to bend without breaking and return to shape.

Malleability

Ability to be reshaped.

Think:

Clay = highly malleable

45. PARAGRAPH COMPREHENSION ⭐

This section is actually very manageable.

You'll get a paragraph and questions.

Four big question types

1. Detail
"What does the paragraph say?"

→ Find it directly.

2. Main idea
"What is this paragraph mostly about?"

→ Don't get distracted by one detail.

3. Purpose
"Why did the author write this?"

→ Ask what the paragraph is trying to accomplish.

4. Inference
"What can you reasonably conclude?"

→ Use ONLY information from the paragraph.

BEST STRATEGY

Read the question first.

Then read the paragraph looking for the answer.

Don't use outside knowledge unless the question clearly requires it.

46. WORD KNOWLEDGE ⭐

This is basically vocabulary.

If you know the word

Pick the closest definition.

If you don't know it

Break it apart.

Prefixes

un- = not

re- = again/back

dis- = opposite/not

mis- = wrong/bad

semi- = half/partly

anti- = against

Suffixes

-less = without

-ful = full of

-ly = in a certain manner

-er = one who / comparative

-est = most

-able = capable of

-ous = full of/having

Root words

The root gives you the core meaning.

Context clues

Look at the words around an unfamiliar word.

If the sentence says:

"He was extremely reluctant to go, repeatedly refusing to leave."

You can infer reluctant = unwilling.

🔥 THE 25 THINGS I WOULD MEMORIZE TONIGHT

If you're running out of time, memorize these before anything else:

PEMDAS
D = RT
Percent = part ÷ whole × 100
Probability = favorable ÷ total
a² + b² = c²
Rectangle area = LW
Triangle area = ½BH
Circle area = πr²
Circumference = 2πr
V = IR
P = VI
F = ma
Work = Force × Distance
Kinetic = motion
Potential = stored
Newton 1 = inertia
Newton 2 = F = ma
Newton 3 = equal/opposite
Engine = Intake → Compression → Power → Exhaust
Gas engine = spark
Diesel = compression heat
Piston → connecting rod → crankshaft
Camshaft controls valves
Series = one path
Parallel = multiple paths

⏰ Your next 10 hours

Don't spend all 10 hours studying straight.

First 3 hours: Math + Arithmetic Reasoning
Next 2 hours: Mechanical + Electronics
Next 1.5 hours: Auto/Shop
Next 1.5 hours: General Science
Next 1 hour: Word + Paragraph Comprehension
Final hour: Review the 25 things above + sleep.

Seriously: sleep. Going into the test exhausted can hurt more than squeezing in another hour of studying.

If you want the highest possible score improvement tonight, the best move after reading this is to do ASVAB-style practice questions, especially Arithmetic Reasoning, Math Knowledge, Mechanical, and Electronics.