Significant Figure Rules

i. Rule 1: All nonzero digits are significant.

Ex. 12, 235 = 5 significant digits

i. Rule 2a: Zeros are significant when found between 2 nonzero digits.

Ex. 250.6 = 4 significant digits

ii. Rule 2b: Zeros are significant when found after a decimal point.

Ex. 5.00 = 3 significant digits; 2.0 = 2 significant digits

iii. Rule 2b: Zeros are significant when found after a nonzero digit in a decimal number.

Ex. 5.030 = significant digits

iv. Rule 3a: Zeros are not significant when used as a place indicator. …

Ex. 0.003 = 1 significant digit

v. Rule 3b: Zeros are not significant when used to call attention to a decimal point. …

Ex. 0.003 = 1 significant digit

vi. Rule 4: Zeros at the end of a number without a decimal point may or may not be significant. We remove the ambiguity by using scientific notation.

Ex. 30, 000 = 1, 2, 3, 4, or 5 significant digits;

3 x 10⁴ = 1 significant digits

3.0 x 10⁴ = 2 significant digits

3.00 x 10⁴ = 3 significant digits

3.000 x 10⁴ = 4 significant digits

3.0000 x 10⁴ = 5 significant digits