Answer:
7 × 10^9
20
Explanation:
First question:
7,125,000,000
Place a decimal point to the right of the 7.
7.125
Look in the original number. How many decimal places are there from the right of the 7 until after the ones digit?
7,125,000,000
There are 9 decimal places, so the exponent of the 10 is 9.
7,125,000,000 = 7.125 × 10^9
Round 7.125 to 7:
7 × 10^9
Answer: 7 × 10^9
Second question:
U.S. population in 2014 was 318,000,000, or approximately 3 × 10^8.
7 × 10^9 / 3 × 10^8 = 70/3 = 23.333...
Answer: 20