Rounding Decimal Numbers

1
Rounding Decimal Numbers

• Sometimes close enough is good enough!

2
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?
4
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!
5
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
Find your number
Look right next door
Four or less, just ignore Five or more, add one
more
7
474 Rounded to the hundreds becomes 500
Round 474 to the closest 10s
474
Just ignore - 470
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Try These

• 4,215
• 394
• 27
• 127,591
• 638

9
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
4.17
10
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?
12
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
13
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
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Homework
Page 600 Lesson 3-3 at the top of the page 1-20