Question Video: Rounding Two-Digit Numbers to the Nearest Ten

Which of the following numbers will give 30 when rounded to the nearest ten? [A] 31 [B] 10 [C] 24 [D] 36

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Video Transcript

Which of the following numbers will give 30 when rounded to the nearest ten? 31, 10, 24, or 36.

We have to decide which of the four numbers will round to 30 if we rounded to the nearest ten. Where would we place the number 31 on the number line? The three digit in 31 is worth three 10s, which are 30. So, we know that 31 comes after 30 on the number line. The 10 which comes after 30 is 40. Number 31 comes between 30 and 40 on the number line. 35 is halfway between these two 10s. We could position number 31 about here on the number line. We know when we’re rounding a number to the nearest ten, we have to look at the ones digit. If the ones digit is less than five, we round down.

The number 31 has one in the ones place. And we know that one is less than five, so we have to round down. 31 rounded to the nearest ten is 30. So, we know that number 31 will round to 30 if we rounded to the nearest ten. The nearest ten to the number 10 is 10. The nearest ten to the number 24 is 20. Four is less than five, so we round down to 20. And the number 36 has three tens and six ones. So, we need to round up to the nearest ten, which is 40. The number which will give 30 when rounded to the nearest ten is the number 31.

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