# 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 are taught in your class.

Regardless of what your instructor or textbook teaches, you must follow the rules listed here to receive credit for answers that are required to be specified to a certain number of significant figures. If your instructor or textbook teaches significant figures differently than these rules, tell your instructor. Your instructor can turn off significant figure checking for 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