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Significant Figures 3

Addition/Subtraction

Method for addition and subtraction involving significant figures:

- Determine the number with the smallest number of significant figures to the
*right*of the decimal point. The digits to the left of the decimal point do not contribute to determing the number of significant digits in the answer. - Add and subtract all numbers using all available digits.
- Round the answer so that the decimal portion has the same number of digits as that in the number determined in step one.

Perform the following calculations and report answer with the correct number of significant figures.

- 6.8 m + 4.79 m + 3.99 m – 3.9801 m
- 14.2 g + 16.9 g + 12.04 g
- 96.2 mL – 91.03 mL
- 7.3 L – 4.93 L
- 34.9 mg + 47.22 mg
- 5.7 m + 5.8 m + 4.99 m
- 47.9 mL – 37.31 mL
- Find the average: 5.05 cm 4.99 cm 5.2 cm 4.9 cm

- Find the average: 321 nm 332.2 nm 314.33 nm
- A house has two bedrooms. One bedroom is 4.7 m × 5.34 m and the other is 6.98 m × 7.32 m. What is the total area of the two bedrooms?
- The volume of a cylinder can be found by multiplying the area of the base by the height:

V = πr^{2}h. What is the total volume, in mL, of two cylinders with the following measurements:

Cyl. 1 r_{1}= 2.3 cm, h_{1}= 4.79 cm

Cyl. 2 r_{2}= 4.79 cm, h_{2}= 4.60 cm - What is the new volume if 989.3 m
^{3}of water in a large tank has 1 tablespoon removed from it?