# How WebAssign Calculates Significant Figures

Because textbooks and instructors sometimes use different rules for determining significant figures, WebAssign might calculate the "correct" number of significant figures in a different way than you teach in your class.

If you teach significant figures using different rules than are listed here, do not enable significant figure checking in your assignments.

## Rules for Significant Figure Calculations in WebAssign

Operation Rule Examples

Use the fewest number of decimal places specified in any of the operands.

10 + 1 = 10
2.46 + 6.1743 = 8.63

Subtraction

Use the fewest number of decimal places specified in any of the operands.

10 - 1 = 10
3.1415 - 2.2 = 0.9

Multiplication

Use the fewest number of significant figures specified in any of the operands.

1530 × 4.0 = 6100
1530 × 4 = 6000

Division

Use the fewest number of significant figures specified in any of the operands.

444 ÷ 4 = 100
444 ÷ 111 = 4.00

Exponentiation

Use the same number of significant figures as the base.

210 = 1e3
2.00010 = 1024

Logarithms

Use the same number of decimal places in the result as the number of significant figures in the number you are taking the logarithm of.

log10(27) = 1.43
ln(0.026) = -3.65

Antilogarithms

Use the same number of significant figures in the result as the number of decimal places in the number you are taking the antilogarithm of.

103.43 = 2700
e-3.65 = 0.026