Rounding Decimal Numbers

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Rounding Decimal Numbers

• Sometimes close enough is good enough!

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Molly has 16 in her pocket

• She buys
• 3 hotdogs _at_ 1.89 each
• 3 milkshakes _at_ 2.19 each
• 3 Large French fries _at_ 1.79 each

Does she have enough money?
3
Gas costs 1.79 per gallon
Im running on empty and I have a 20 gallon tank
on my truck About how much will it cost to
fill up?
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You have one hour to take a 50 question test.
About how much time can you spend on each
question?
Close enough is good enough!
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The rounding poem
Find your number Look right next door 4 or less,
just ignore 5 or more add one more!
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Rounding Whole Numbers
Round 474 to the closest hundred.
474
Five or more, add one more.
Four or less, just ignore.
474 Rounded to the hundreds becomes 500.
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Rounding Whole Numbers
Round 474 to the closest 10s
474
Four or less, just ignore.
474 Rounded to the tens becomes 470.
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Try to round off these numbers

• 4,215 (to nearest hundred)
• 394 (to nearest ten)
• 27 (to nearest ten)
• 127,591 (to nearest thousand)
• 638 (to nearest hundred)

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What about decimal numbers ?
The same rules (and poem) apply!
Round 4.167 to the closest hundredths.
4.167
Find your number.
Look right next door.
Answer 4.17
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Remember
If you are asked to round to the nearest
tenth.your answer stops at the tenth place!
Example Round 42.73 to the closest tenth would
be 42.7
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Special Case!Rounding a 9
Round 2.197 to the closes hundredths
Since there is a 9 in the hundredths place
consider the tenth and hundredths together 19
do you leave it at 19 or move it to 20?
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Round 4.95 to the closest tenth
Since there is a 9 in the tenth spot consider
the ones and tenths together should you leave
it at 49 or move it to 50?
4.95 rounded to the nearest tenth is 5.0
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Try these
Round to hundredths
Round to tenths
4.56
4.6
18.784
18.78
5.32
5.3
9.46
9.456
10.00
0.98
1.0
9.997