Homework 4-1
Name
Arrays and Using an
Expanded Algorithm
Another Look!
You can use arrays of place-value
blocks to multiply.
Find 3 × 114.
What You Show
What You Write
114
3
12
30
+ 300
342
×
3 × 4 ones
3 × 1 ten
3 × 1 hundred
The partial products are modeled by
the blocks! See, there are 12 unit cubes,
3 tens rods, and 3 hundreds blocks.
Leveled Practice In 1 through 4, use place-value blocks
or draw an array to help you complete each calculation.
1.
2 1 8
×
4
2.
223
× 5
4.
□
□□
+ □□□
□□□
□□
□□
+ □□□
□□□
3.
4 1 1
×
2
316
× 3
Topic 4 Lesson 4-1
227
5. Which partial products and final product
complete the calculation?
3 2 7
×
3
□□
□□
+ □□□
□□□
A
B
C
D
6. Communicate Show how you can use an
array to find partial products for 4 × 125.
Use place value
to find partial
products.
21, 6, 9, 36
21, 60, 90, 171
21, 60, 900, 981
21, 6, 90, 117
7. Number Sense What three simpler
multiplications can you use to find 8 × 242?
8. Mental Math Describe how you would
find 24 + 36 using mental math.
9. A red tree frog can jump up to 150 times
its body length. How far can this tree frog
jump?
5 cm
10. Estimation Juan multiplied 4 × 304 to
get 1,216. Use estimation to check the
reasonableness of Juan’s answer.
11. Gary asked his mother how old she was
when he was born. His mother said, “You
were born in 2003. I was born in 1979.
Subtract 1979 from 2003 to find how old
I was when you were born.” How old was
Gary’s mother when he was born?
228
12. Extend Your Thinking Tony says that to
multiply 219 × 3, you multiply 2 × 3,
1 × 3, and 9 × 3, then add the products.
Explain Tony’s error. How would you
help Tony understand how to correctly
multiply 219 × 3.
© Pearson Education, Inc. 4