Rounding
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How to Round Numbers
Example: Round 74 to the nearest 10
(74 gets "rounded down")
Example: Round 86 to the nearest 10
(86 gets "rounded up")
- Decide which is the last digit to keep
- Leave it the same if the next digit is less than 5 (this is called rounding down)
- But increase it by 1 if the next digit is 5 or more (this is called rounding up)
Example: Round 74 to the nearest 10
- We want to keep the "7" as it is in the 10s position
- The next digit is "4" which is less than 5, so no change is needed to "7"
(74 gets "rounded down")
Example: Round 86 to the nearest 10
- We want to keep the "8"
- The next digit is "6" which is 5 or more, so increase the "8" by 1 to "9"
(86 gets "rounded up")
Estimation
Being able to estimate is an important tool when it comes to any operation we do in Math. It lets us know if our answers makes sense and are reasonable. It's not an exact answer but close enough to let us know if we're in the right neighborhood.