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.
