# Question 7b5d6

Sep 22, 2015

a) 15.1+75.32=90.4

b) (5.50xx10^8) * (4xx10^5)=2xx10^14

c) 5.672xx10^(-6)+7.785xx10^(-6)=1.346xx10^(-5)

d) 45.32xx2.3=1.0xx10^2#

#### Explanation:

A and C: When adding or subtracting, look for the number with the fewest decimal places and round the result to the same number of decimal places.

Note on C: When adding numbers in scientific notation, the exponents must be the same.

B and D: When multiplying or dividing, look for the number with the fewest significant figures and round the answer to the same number of significant figures.

Note on D: The answer was $104.236$. To round to two significant figures, you need to use scientific notation. $100$ would have only one significant figure, and $104$ would have three significant figures. But $1.0 \times {10}^{2}$ has two significant figures.