Question

Question : find the exact answer for the following. Then round off the first number to 100 places and the second to 10 places and estimate the answer, mention if the answer is reasonable or not.

A) 145.86 + 79.6
B) 2450.21 - 599.36
C) 922.58 - 398.99
D) 2351.85 + 89​

Answer 1

A) 145.86 + 79.6 = 225.46

Rounding off the first number to 100 places, 145.86 becomes 145.86000

Rounding off the second number to 10 places, 79.6 becomes 79.60000

So the rounded answer is 145.86000 + 79.60000 = 225.46000

Estimated answer: 225

The answer is reasonable.B) 2450.21 - 599.36 = 1851.05

Rounding off the first number to 100 places, 2450.21 becomes 2450.21000

Rounding off the second number to 10 places, 599.36 becomes 599.36000

So the rounded answer is 2450.21000 - 599.36000 = 1851.05000

Estimated answer: 1850

The answer is reasonable.C) 922.58 - 398.99 = 523.59

Rounding off the first number to 100 places, 922.58 becomes 922.58000

Rounding off the second number to 10 places, 398.99 becomes 398.99000

So the rounded answer is 922.58000 - 398.99000 = 523.59000

Estimated answer: 523

The answer is reasonable.D) 2351.85 + 89 = 2440.85

Rounding off the first number to 100 places, 2351.85 becomes 2351.85000

Rounding off the second number to 10 places, 89 becomes 89.00000

So the rounded answer is 2351.85000 + 89.00000 = 2440.85000

Estimated answer: 2440

The answer is reasonable.