Significant Digit Patterns in Arithmetic:
In multiplication and division, the number of significant figures in the answer is the least number of significant figures in the calculation (once rounded). For example:
4.56 * 1.4 = 6.38 rounded-> 6.4
4.56 / 1.4 = 3.25 rounded-> 3.3
As the above examples demonstrate, both answers have two significant digits, the least amount in the calculation (1.4 has two significant digits).
In addition and subtraction, the answer has the same number of decimal places as the least precise measurement used in the calculation (after rounded). For example:
12.11 + 18.0 + 1.013 = 31.123 rounded-> 31.1
18.0 - 12.11 - 1.013 = 4.877 rounded-> 4.9
In both cases, the answer has 1 decimal place, because the least precise measurement, 18.0, only has 1 decimal place.