Question

Question 9 - (3 marks available)
By rounding to 1 significant figure, estimate the answers to these questions:
a) 17 * 82
b) 54 x 671
c) 207 x 643​

Answer 1

Answer: a) 1,600

              b) 35,000

              c) 120,000

Step-by-step 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