Question

Two patterns of whole numbers are as follows: ​
120, 116, 112, A, 104, …​
45, 47, 49, B, 53, …​

Estimate the value of A $\times$ B

• A. 4000
• B. 5000
• C. 6000
• D. 10,000

Answer 1

The correct option is B 5000

In the first pattern,

120, 116, 112, A, 104, …​

As we move forward, the numbers keep decreasing by 4.

So, A = 112 - 4 = 108


For the second pattern

45, 47, 49, B, 53, …​

As we move forward, the numbers keep increasing by 2.

So, B = 49 + 2 = 51


Now, we’ve to estimate the value of A x B = $108\times 51$

As we know, for product estimation, round off each factor to its greatest place, then multiply the rounded off factors.
108 can be rounded off to 100 and 51 can be rounded off to 50

Estimated value of $108\times 51$ is $100\times 50$ = 5000

So, option ‘b’ is the correct answer.