Question

Estimate the value of the product $87 \times 313$ .

Answer 1

Hint: Firstly, round off the numbers 87 and 313 to their nearest 10 and 100 respectively.
Then, to find the estimated value of $87 \times 313$ , multiply the rounded-off numbers.
Thus, we get the estimated value of $87 \times 313$ .

Complete step-by-step answer:
The given product is $87 \times 313$ .
We are asked to find the estimated value for the above product.
So, we have to round off the given numbers to nearest 10 or 100 as required.
The number 87 can be rounded off to 90 as the digit at the unit's place is 7, which is greater than 5, so we replace 7 by 0 and add +1 to the digit at tens place.
Also, the number 313 can be rounded off to 300 as the digits at units and tens place form number 13, which is lesser than 50, so we replace 1 and 3 by 0 and write the digit at hundreds place as it is.
So, the estimated value of the product $87 \times 313 = 90 \times 300 = 27000$ .
Thus, the estimated value of $87 \times 313$ is 27000.

Note: Rounding off to nearest 10 (tens):
If the units place digit of a 2-digit number is greater than 5, replace units place digit by 0 and add +1 to the tens place digit. If the units place digit of a 2-digit number is lesser than 5, just replace units place digit by 0 and write tens place digit as it is.
Rounding off to nearest 100 (hundreds):
If the last 2 place digits of a 3-digit number form a number greater than 50, replace the last two place digits by 0 and add +1 to the hundreds place digit. If the last two place digits of a 3-digit number form a number lesser than 50, just replace the last two place digits by 0 and write hundreds place digits as it is.