Math 6 Unit 02 Notes - Decimals Worksheet Page 8
ADVERTISEMENT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19Math 6 Unit 02 Notes – Decimals
Estimation
An estimation strategy for adding and subtracting decimals is to round each number to the nearest
whole number and then perform the operation.
Examples:
≈
≈
25.8
26
7.98
8
−
≈ −
−
≈ −
14.2
14
6.2
6
12
2
2 would be our estimate
12 would be our estimate
An estimation strategy for multiplying and dividing decimals:
When multiplying, round numbers to the nearest non-zero number or to numbers that are easy to
multiply.
When dividing, round to numbers that divide evenly (compatible numbers), leaving no
remainders.
Remember, the goal of estimating is to create a problem that can easily be done mentally.
→
÷
→
÷
=
Example:
38.2
40
33.6 4.2
3
2 4
8
×
→
×
6.7
7
28 0
280 would be our estimate
8 would be our estimate
Estimating can be used as a test-taking strategy. Use estimating to calculate your answer first, so you
can eliminate any obviously wrong answers.
Example: A shopper buys 3 items weighing 4.1 ounces, 7.89 ounces and 3.125
ounces. What is the total weight?
A.
0.00395
B.
3.995
C. 14.0
D. 15.115
Round the individual values:
→
4.1
4
→
7.89
8
→ +
3.125
3
15
The only two reasonable answers are C) and D). Eliminating unreasonable answers can help
students to avoid making careless errors.
D is the correct solution.
Sometimes we need a closer estimate without getting an exact answer. Adjusting
the front –end estimation is a method we could use.
Math 6 NOTES
Unit 02: Decimals
Page 8 of 19
2014-15 -NVACS
ADVERTISEMENT
0 votes
Related Articles
Related forms
Related Categories
Parent category: Education