Significant Figure Guidelines
Use these rules to determine the significant figures in a number. The significant figures
are underlined in each example.
1. Count all non-zero digits. 36 has 2 sig figs
2. ALWAYS count zeros that are sandwiched in between two non-zero digits.
306 has 3 sig figs
520.009 has 6 sig figs
3. ONLY count zeros to the right of non-zero digits IF there is a decimal point
written in the number.
7700 has 2 sig figs
3.00 has 3 sig figs
50.300 has 5 sig figs
4. NEVER count zeros that are by themselves to the left of non-zero digits
0.008 has 1 sig fig
0.6703 has 4 sig figs
Practice: Underline the significant figures in each number
10.05
0.1005
0.002030
23,000,000
6.250
9.067
0.04010
3.00
909
0.500
670,000.
0.800008
0.00881
34.802
2,700
0.0007
Addition or Subtraction
When adding or subtracting numbers your answer can only have as many decimal places
as the number with the least amount of decimal places.
1.22
+2.5_
3.72  3.7
(only 1 decimal place allowed)
3.45556
-1.33____
2.12556  2.13
(only 2 decimal places allowed)
Practice: Give the following answers with the correct number of significant figures:
30.4 + 52.12 = ______
8.21 + 10.365 = ______
56.002 + 6.221 = ______
45.2 + 555 = ________
95.236 – 9.00 = _______
62.5488 – 1.2 = _______
5.0 – 2 = ______
189.25698 – 6.322 = ________
Multiplication or Division
When multipliyng or dividing numbers, the answer can only have as many significant
figures as the number with the least amount of significant figures.
3.03 X 120 = 363.6  360
(only 2 sig figs allowed)
6.25 / 30 = 0.20833  0.2
(only 1 sig fig allowed)
Practice: Give the answers with the correct number of significant figures
6.93 X 36 = _________
540 X 5.0 = ________
98.23 X 2.31 = ________
82 X 56.35 = _________
9.0 / 3 = ________
45.3 / 9.1 = ________
2.17 / 7.0 = ______
54.8 / 16.00 = _______