Answer: a) 1,600
b) 35,000
c) 120,000
Explanation:
First, round each number to one significant digit (the first digit).
Then multiply them.
a) 17 --> rounds to 20
82 --> rounds to 80
20 x 80 = 2 x 8 with two zeros
= 1 6 0 0
b) 54 --> rounds to 50
671 --> rounds to 700
50 x 700 = 5 x 7 with three zeros
= 3 5 0 0 0
c) 207 --> rounds to 200
643 --> rounds to 600
200 x 600 = 2 x 6 with four zeros
= 1 2 0 0 0 0