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Rounding to the nearest tens or hundreds place means finding the closest number
with no tens and no ones. (Making it a "friendlier" number)
Examples: 678 can be rounded to 70051 can be rounded to 50
Can you come up with a few examples?
What is rounding?
Sometimes, you do not need an exact answer. You could be giving an estimate. In
that case, it makes it easier to round a number to the nearest tens or hundreds
place.
Discuss opportunities that may require you to estimate.
Why do we round?
Remember this problem? 28 + 56
We would rather answer 30 + 60 because the numbers are friendlier.
Our answer is close, but not exact.
What makes them friendlier?(They end in zero!)
"Friendly" Numbers
Using the number line, decide if 0 or 10 is the friendly number for each number.
Create a T-Chart.
Partner Time
● If the number you are rounding is followed by 5, 6, 7, 8, or 9, round the number up.○ Example: 38 rounded to the nearest ten is 40
● If the number you are rounding is followed by 0, 1, 2, 3, or 4, round the number down.○ Example: 32 rounded to the nearest ten is 30.
Rules for rounding
Find the digit,
Look next door
Five or higher,
Add one more
Four or less,
Let it rest!
The Rounding Rhyme