rounding
'5' is the magic number
When rounding, we use the number 5 as the magic number. When the digit we are looking at is 5 or more we ROUND UP. When the digit we are looking at is less than 5 (4, 3, 2, 1, 0), then we ROUND DOWN.
ROUND 26 to the nearest TEN.
The number 26 is between 20 and 30. Which MULTIPLE OF TEN is it CLOSEST to?
20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
We can see that 26 is closer to 30 than it is to 20. So it is rounded to 30.
But because the 6 in 26 is 5 or more (5, 6, 7, 8, 9), then we ROUND UP to 30
ROUND 42 to the nearest TEN.
The number 42 is between 40 and 50. Which MULTIPLE OF TEN is it CLOSEST to?
40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50
We can see that 42 is closer to 40 than it is to 50. So it is rounded to 40.
But because the 2 in 42 is less than 5 (4, 3, 2, 1, 0), then we ROUND DOWN to 40
ROUND 26 to the nearest TEN.
The number 26 is between 20 and 30. Which MULTIPLE OF TEN is it CLOSEST to?
20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
We can see that 26 is closer to 30 than it is to 20. So it is rounded to 30.
But because the 6 in 26 is 5 or more (5, 6, 7, 8, 9), then we ROUND UP to 30
ROUND 42 to the nearest TEN.
The number 42 is between 40 and 50. Which MULTIPLE OF TEN is it CLOSEST to?
40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50
We can see that 42 is closer to 40 than it is to 50. So it is rounded to 40.
But because the 2 in 42 is less than 5 (4, 3, 2, 1, 0), then we ROUND DOWN to 40
rounding to 10, 100, 1000
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We can round numbers to the nearest 10, 100, 1000 by looking at the digit to the RIGHT of the place we are rounding to.
Example: Round 29 to the nearest 10. (2 is in the tens column, so look to the right at 9) 9 is greater than 5 so ROUND UP to 30 Example: Round 542 to the nearest 100. (5 is in the hundreds column, so look to the right at 4) 4 is less than 5 so ROUND DOWN to 500 Example: Round 7,604 to the nearest 1000. (7 is in the thousands column, so look to the right at 6) 6 is greater than 5 so ROUND UP to 8000 |
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