Worked Examples
34 numbers, grouped by the rule each one tests. These are the cases that trip people up, not a list of every number.
Leading zeros
Zeros before the first non-zero digit only place the decimal point.
Trailing zeros after a decimal point
Written to record precision, so they count.
Ambiguous whole numbers
No decimal point, so the notation cannot say how many are meant.
Zeros in the middle
Always significant — they sit between digits that are.
Scientific notation
Only the mantissa carries significant figures.
Straightforward
No zeros to argue about.