Question

Question 179

Estimate each of the following products by rounding off each number to nearest tens.

(a) 87 x 32

(b) 311 x 113

(c) 3239 x 28

(d) 1385 x 789

Answer 1

(a) We have, 87 x 32

Rounded off 87 to nearest tens = 90

and rounded off 32 to nearest tens = 30

So, estimated product = 90 x 30 = 2700

(b) We have, 311 x 113

Rounded off 311 to nearest tens = 310

and rounded off 113 to nearest tens = 110

So, estimated product = 310 x110 = 34100

(c) We have, 3239 x 28

Rounded off 3239 to nearest tens = 3240

and rounded off 28 to nearest tens = 30

So, estimated product = 3240 x 30 = 97200,

(d) We have, 1385 x 789

Rounded off 1385 to nearest tens = 1390

and rounded off 789 to nearest tens = 790

So, estimated product = 1390 x 790 = 1098100.