Math Vocabulary

Vocabulary

For some math questions, the only hard part is knowing the vocabulary, and once you know the terms, the questions are easy. Memorize the terms and practice using them in the drills. Also, once you know the terms, watch for them and underline them when they appear. That will eliminate many careless errors.

Here are some useful math vocabulary terms:

Rational number: A number that can be expressed as the quotient of two integers and has a finite number of decimal places, or has decimal values that repeat in a pattern.

Irrational number: A number that cannot be expressed as the quotient of two integers and has an infinite number of decimal places. Examples: 3.1415926535897932348…, e (2.7182818284590…), etc.

Real number: Any number without an “i” to mean “imaginary number.” or ∞. Examples: −3, −2.2, 0, 2.75, 3.1415926535897932348…(pi again!), and 2⎯⎯√2

Constant: This word really throws some kids, but it just means a letter in place of specific, fixed number, just like a variable. Sometimes we may know the numerical value of the constant, sometimes we won’t.

Integer: Numbers without decimals or fractions. Also known as a whole number. Examples: −3, −2, −1, 0, 1, 2, 3…

Even/Odd: Even numbers: 2, 4, 6, 8…; odd numbers: 1, 3, 5, 7… The number 0 is considered even.

Adding Odd and Even Numbers

• ODD + ODD = EVEN
• ODD + EVEN = ODD
• EVEN + EVEN = EVEN

Positive/negative: Positive numbers are greater than 0. Negative numbers are less than 0.

Consecutive numbers: Numbers that are next to each other: 5 and 6, 100 and 101, 9 and 10…you get the picture. Just add 1 to get from the first number to the second. If a question problem says “Two consecutive numbers” and doesn’t tell you what they are, label them as “x” and “x + 1.” If they ask for “Three consecutive numbers,” label them as “x” and “x + 1” and “x + 2.”

Consecutive even/odd numbers: Pairs of even numbers and odd numbers that are next to each other (skipping the odd and even numbers, respectively, between them): 2 and 4, 57 and 59, 100 and 102…you get the picture. Just add 2 between each number. If a problem says “Two consecutive even numbers” or “Two consecutive odd numbers” and doesn’t tell you what they are, label them as “x” and “x + 2.” If it asks you for “three consecutive even/odd numbers,” that means “x,” “x + 2,” and “x + 4”.

Prime: A number whose only factors are 1 and itself. The numbers 2, 3, 5, 7, 11, 13, 17, …are prime.

The number 1 is not considered prime, and the number 2 is the only even prime number.

To create a list of prime numbers: List all the odd numbers and the number 2. Eliminate all perfect squares. Eliminate all numbers ending in 5. Then eliminate any number divisible by 3. Finally, eliminate any number divisible by 7. The remaining list should be a complete list of prime numbers.

Units digit: Just a fancy term for the “ones” digit in a number, like the 2 in 672.