Summary

1. Rounding.
2. The rule in multiplication and division is that the final answer should have the same number of significant figures as there are in the number with the fewest significant figures.

When you add or subtract, you assign significant figures in the answer based on the number of decimal places in each original measurement. When you multiply or divide, you assign significant figures in the answer based on the smallest number of significant figures from your original set of measurements.

1. To round to three significant figures, look at the fourth significant figure. It’s a 5 , so round up.
2. To round to four significant figures, look at the fifth significant figure. It’s a 1 , so round down.
3. To round to two significant figures, look at the third significant figure. It’s an 8 , so round up.

To round to a significant figure:

1. look at the first non-zero digit if rounding to one significant figure.
2. look at the digit after the first non-zero digit if rounding to two significant figures.
3. draw a vertical line after the place value digit that is required.
4. look at the next digit.

When multiplying numbers written in exponential notation:

1. Multiply digit terms in the normal fashion.
2. Obtain the exponent in the product by adding the exponents of the factors multiplied.
3. If necessary, adjust the exponent to leave just one digit to the left of the decimal point.

Any numbers in scientific notation are considered significant. For example, 4.300 x 10-4 has 4 significant figures.

Calculator Use. Round a number to a quantity of significant figures that you provide. In rounding significant figures, when an integer contains more digits than are significant, the last significant digit has an overline to indicate that it is the last significant digit. Enter whole numbers, real numbers, scientific notation or e notation.

When rounding significant figures the standard rules of rounding numbers apply, except that non-significant digits to the left of the decimal are replaced with zeros. Example: 356 rounded to 2 significant digits is 3 6 0

When multiplying significant digits, the amount of significant figures in the final product is determined by the number of significant digits in each of the multiplicands. The product can only have as many significant digits as the multiplicand with the least amount of significant digits.

Our significant figures calculator works in two modes – it performs arithmetic operations on multiple numbers (for example, 4.18 / 2.33) or simply rounds a number to your desired number of sig figs. Following the rules noted above, we can calculate sig figs by hand or by using the significant figures counter.