Decimals Worksheet - Unit 3 Page 8
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38® A ping-pong ball has a mass of 2.73 g.
Estimate the mass of 8 ping-pong balls.
Here are two strategies students used to estimate: 2.73
8
• Lara used front-end estimation.
She wrote 2.73 as 2.
In front-end estimation , we
use the place value of the
Then multiplied: 2
8
16
front digits of a number.
The mass of 8 ping-pong balls is about 16 g.
This is an underestimate because 2 is less than 2.73.
• Hal used decimal benchmarks.
Since 2.73 is closer to 3 than to 2,
he wrote 2.73 as 3.
2.73
Hal multiplied: 3
8
24
1
2
3
4
The mass of 8 ping-pong balls is about 24 g.
This is an overestimate because 3 is greater than 2.73.
® Four baseballs have a total mass of 575.94 g.
Estimate the mass of 1 baseball.
Here are two strategies students used to estimate: 575.94
4
• Aki used front-end estimation.
He wrote 575.94 as 500.
Then divided: 500
4
125
The mass of 1 baseball is about 125 g.
This is an underestimate because 500 is less than 575.94.
• Adele looked for compatible numbers.
Compatible numbers are
numbers that are easy
Since 575.94 is close to 600,
to use mentally.
she divided: 600
4
150
The mass of 1 baseball is about 150 g.
This is an overestimate because 600 is
greater than 575.94.
93
Unit 3 Lesson 2
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