PHY C1: Prefixes, Standard Form and Significant Figure

What are Prefixes?

Symbols used to indicate decimal sub-multiples or multiples of both base and derived units.

What are some common Prefixes and their Multiples/Sub-multiples?

pico (p) 10⁻¹², nano (n) 10⁻⁹, micro (μ) 10⁻⁶, milli (m) 10⁻³, centi (c) 10⁻², deci (d) 10⁻¹, kilo (k) 10³, mega (M) 10⁶, giga (G) 10⁹, tera (T) 10¹².

What is Standard Form?

Expresses a number as N × 10ⁿ, where n is an integer (positive or negative) and N is any number such that 1 ≤ N ≤ 10.

What are Significant Figures?

Digits in a number that contribute to its precision.

When are zeroes on the left of the first non-zero digit significant?

Never.

When are zeroes on the right of the last non-zero digit significant?

Only after a decimal point.

How is the number of significant figures determined?

By the resolution of instruments used or the significant figures of other quantities in a calculation. Assume 3 s.f. if in doubt.