How Many Significant Figures Are in 0.0005?
0.0005= 1 significant figure
Why 0.0005 has 1 sig fig
0.0005 has four leading zeros before the digit 5. All leading zeros are never significant — they only show where the decimal goes. The digit 5 is the only significant figure. There are no trailing zeros after the decimal following the 5, so there is no ambiguity.
Rule applied
Leading zeros are never significant (Rule 3). Non-zero digits are always significant (Rule 1). See full rule →
Edge case note for 0.0005
In scientific notation: 5 × 10⁻⁴. Clearly 1 sig fig. If the measurement had more precision, it would be written as 5.0 × 10⁻⁴ (2 sf) or 5.00 × 10⁻⁴ (3 sf).