Math 10 - Significant Digits Review

Rule: When adding or subtracting, your answer can only show as many decimal places as the measurement having the least number of decimal places. Round according to the rule.

e.g. 4.64 + 3.2 = 7.84 = 7.8
(2 decimal places) + (1 decimal place) = (1 decimal place)

1. 12 + 4.459
2. 123 - 59.1
3. 45.04 + 1.876
4. 1.421 + 0.4372
5. 0.14 +1.2243
6. 121.01 -14.0
7. 463.231 - 42.18.
8. 7.98 – 12.5
9. 54.8 – 0.002
10. 34.865 + 56.324

Rule: When multiplying or dividing, your answer can only show as many significant digits as the measurement showing the least number of significant digits. Round according to the rule.

e.g. 15.8 x 12.78 = 201.924 = 202
(3 significant digits) x (4 significant digits) = (3 significant digits)


1. 23.2 ÷ 4.1
2. 4.05 x 0.98
3. 0.096 x 12.05
4. 0.61 x 42.1
5. 0.05 x 87
6. 14.6 x 3.4
7. 400 x 2.69
8. 506.90 x 46.78
9. 89.90 x 0.07
10. 6 x 67.98