Video: AF5P1-Q06-312176204648

By rounding each number to the nearest 100, calculate an estimate for (324 × 478)/512. You must show all your working.

02:42

Video Transcript

By rounding each number to the nearest 100, calculate an estimate for 324 multiplied by 478 divided by 512. You must show all your working.

We are asked in the question to round each of the three numbers to the nearest 100. In order to do this, we need to look at the tens digit. If this number is five or greater, we will round up. And if it is less than five, we will round down. Our first number was 324. The number in the tens column is a two. As this is less than five, we will round 324 down to 300. An alternative way of doing this is to look at the number line between 300 and 400. The midpoint here is 350 as it is halfway between 300 and 400. As 324 is less than 350, it is closer to 300, so we round down.

The second number in our question is 478. This time, the number in the tens column is a seven. This means that we will round up. Rounding 478 up to the nearest 100 gives us 500 as 478 is closer to 500 than 400. The final number we need to round is 512. The number in the tens column is a one. And this is less than five. Therefore, we will round down. 512 rounded down to the nearest 100 is 500. Our calculation, therefore, becomes 300 multiplied by 500 divided by 500. As we have a 500 on the top and the bottom on the numerator and denominator, these will cancel. This is because 500 divided by 500 is equal to one. We are, therefore, left with an answer of 300. When rounding each of the numbers in the calculation 324 multiplied by 478 divided by 512 to the nearest 100, the estimated answer is 300.

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