Download x 7 - cloudfront.net

Reteach: Multiply a Double Digit
Number by a Single Digit Number
2
Name:____________________
When you are multiplying a double digit number by a single
digit number
number, it’s
it s important to think about the place value of
the digits. In the example, 24 x 7, the 2 is actually 20,
because it is in the tens place. So the problem is asking
you to solve 20 x 7 plus 4 x 7.
24
x 7
168
Start by multiplying the ones column. 7 x 4 is 28. Write the 8
under the 7
7. Carry the 2
2, which is actually 20
20, over to the
tens column. Next, multiply 7 x 2 is 14. Add the 2 tens that
you carried over from 28. 14 + 2 = 16. Write it next to the 8.
The total of 24 x 7 is 168.
Another way to solve this kind of
problem is to use distributive
property boxes to find partial
products, then add the partial
products together to find the total.
x
20
7
140
+
4
28
140
+ 28
168
Solving the same problem in more than one way is a good strategy
for justifying your answer so you know you are correct.
Guided Practice
Solve each of the problems below using the standard algorithm . Check your answers using the
distributive property box method.
1)
2)
3)
36
x 5
27
x 9
16
x 5
Start with the ones.
Write down the ones in
your answer. Carry the
tens to the tens column.
Multiply the tens, add the
number you carried.
X
30
+
6
5
Start with the ones.
W it down
Write
d
the
th ones in
i
your answer. Carry the
tens to the tens column.
Multiply the tens, add the
number you carried.
X
20
+
7
9
Start with the ones.
Write down the ones in
your answer. Carry the
tens to the tens column.
Multiply the tens, add the
number you carried.
X
10
+
6
5
Add the partial products:
+
__________________
Add the partial products:
+
__________________
Add the partial products:
+
__________________
Independent Practice: Multiply A Double
Digit Number By A Single Digit Number
Name:______________________
Solve the problems below using the standard algorithm. Check your answers using the
distributive property box method.
x
1)
24
x 7
x
Add the p
partial p
products:
+
2)
+
__________________
23
x 8
x
3)
46
x 8
89
x 5
+
x
7)
9)
28
x 6
34
x 5
+
x
+
x
11) 23
x 9
+
x
13) 14
x 5
15) 44
x 3
4)
+
__________________
+
+
x
+
+
__________________
x
Add the partial products:
x
5)
Add the p
partial p
products:
+
Add the partial products:
+
__________________
Add the partial products:
+
__________________
Add the partial products:
+
__________________
Add the partial products:
+
__________________
Add the partial products:
+
__________________
+
x
6)
+
__________________
Add the partial products:
52
x 6
12
x 3
+
x
8)
39
x 4
10) 41
x 3
+
x
+
x
12) 32
x 5
+
x
14) 48
x 7
16) 76
x 9
+
x
+
Add the partial products:
+
__________________
Add the partial products:
+
__________________
Add the partial products:
+
__________________
Add the partial products:
+
__________________
Add the partial products:
+
__________________
Add the partial products:
+
__________________
Add the partial products:
+
__________________