BLOCK 2
TOPIC 2
Estimate and Compare Products
LESSON 2
CONCEPT
1
Estimate the product.
2
Estimate the product.
Estimate the product.
6 3 723
5 3 614
3 3 487
Estimate: 3 3 500
5 1500
Rename the 3-digit factor.
Estimate:
3
5
Estimate:
3
5
Rename the 3-digit factor.
Rename the 3-digit factor.
Find the partial products
Find the partial products
Add the partial products.
Add the partial products.
3 × (400 + 80 + 7)
Find the partial products.
(3 × 400) + (3 × 80) + (3 × 7)
3 × 400 = 1200
3 × 80 = 240
3 × 7 = 21
Add the partial products.
1200
240
+ 21
1461
3 3 487 5 1461
Is your answer reasonable? yes
6 3 723 5
Is your answer reasonable?
72
5 3 614 5
Is your answer reasonable?
MATH 180 Block 2 › Topic 2
070-071_m180_msp_11_b2t2d2.indd 72
1/18/13 10:57 AM
estimate (n) A number that is close to
the exact answer.
estimate (v) To approximate a calculation
using numbers that are easier to work with.
3
4
› Answer this question.
7 3 296
Estimate:
3
Estimate:
3
2
Is 5600 a reasonable estimate
for the product of 7 3 841?
Why or why not?
4 3 438
5
BLOCK
5
5600 is/is not a reasonable
estimate for the product of
7 x 841 because
If my estimate is close
to the product I found,
I know my solution
is probably correct.
7 3 296 5
Is your answer reasonable?
4 3 438 5
Is your answer reasonable?
SCORE
Strategies for Multiplication 73
070-071_m180_msp_11_b2t2d2.indd 73
1/18/13 10:57 AM