rounding - home | cpalms.org you do not need an exact answer. you could be giving an estimate. in...
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RoundingTo the nearest tens and to the nearest hundreds
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
Which is friendlier, 0 or 10?● 2● 6● 8● 4
Find the Friendly Numbers!
Using the number line, decide if 0 or 10 is the friendly number for each number.
Create a T-Chart.
Partner Time
Which is friendlier, 0, 10, or 20?● 13● 18● 5● 11● 2
Find the Friendly Numbers!
Which is friendlier, 0, 10, or 20?● 13● 18● 5● 11● 2
Find the Friendly Numbers!
● 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
Round to the nearest 10.
45 47
19 24
73 87
Round to the nearest 100.
532 945
894 396
Find the digit,
Look next door
Five or higher,
Add one more
Four or less,
Let it rest!
The Rounding Rhyme
Round to the nearest 10:
72
Use the Rounding Rhyme!
Some Practice...
Round to the nearest 10:
72
"Find the digit..."
onestens
Round to the nearest 10:
72
"Look next door..."
Round to the nearest 10:
72
Five or higher? NO
Round to the nearest 10:
72 70
Four or less? Let it rest!
Let's Try Again!
Round to the nearest 100:
586
Use the Rounding Rhyme!
Some More Practice...
Round to the nearest 100:
586
"Find the digit..."
onestenshundreds
Round to the nearest 100:
586
"Look next door..."
Round to the nearest 100:
586
Five or higher? ADD ONE MORE!
Round to the nearest 100:
586 600
Five or higher? ADD ONE MORE!