Question

lesson 18 multiplying 2 digits by 2 digits
multiply 9 ones by 7
put 6 tens above the 1
multiply 1 ten by 7
then, add 6 tens.
multiply 9 ones by 20
put 1 hundred above the 1.
multiply 1 ten by 20.
then, add 1 hundred.
multiply
1.
a
22
×33
b
11
×45
c
80
×10
d
31
×23
e
13
×12
f
30
×31
2.
41
×21
32
×20
40
×10
21
×31
30
×30
14
×10
3.
22
×44
14
×20
40
×12
90
×10
13
×13
30
×11
4.
70
×11
12
×11
81
×10
24
×12
40
×22

Explanation:

Step1: Multiply by ones digit (1a)

First, multiply 22 by 3 (ones place of 33):
$22 \times 3 = 66$
Then multiply 22 by 30 (tens place of 33):
$22 \times 30 = 660$
Add the two results: $66 + 660 = 726$

Step2: Multiply by ones digit (1b)

Multiply 11 by 5:
$11 \times 5 = 55$
Multiply 11 by 40:
$11 \times 40 = 440$
Add: $55 + 440 = 495$

Step3: Multiply by ones digit (1c)

Multiply 80 by 0:
$80 \times 0 = 0$
Multiply 80 by 10:
$80 \times 10 = 800$
Add: $0 + 800 = 800$

Step4: Multiply by ones digit (1d)

Multiply 31 by 3:
$31 \times 3 = 93$
Multiply 31 by 20:
$31 \times 20 = 620$
Add: $93 + 620 = 713$

Step5: Multiply by ones digit (1e)

Multiply 13 by 2:
$13 \times 2 = 26$
Multiply 13 by 10:
$13 \times 10 = 130$
Add: $26 + 130 = 156$

Step6: Multiply by ones digit (1f)

Multiply 30 by 1:
$30 \times 1 = 30$
Multiply 30 by 30:
$30 \times 30 = 900$
Add: $30 + 900 = 930$

Step7: Multiply by ones digit (2a)

Multiply 41 by 1:
$41 \times 1 = 41$
Multiply 41 by 20:
$41 \times 20 = 820$
Add: $41 + 820 = 861$

Step8: Multiply by ones digit (2b)

Multiply 32 by 0:
$32 \times 0 = 0$
Multiply 32 by 20:
$32 \times 20 = 640$
Add: $0 + 640 = 640$

Step9: Multiply by ones digit (2c)

Multiply 40 by 0:
$40 \times 0 = 0$
Multiply 40 by 10:
$40 \times 10 = 400$
Add: $0 + 400 = 400$

Step10: Multiply by ones digit (2d)

Multiply 21 by 1:
$21 \times 1 = 21$
Multiply 21 by 30:
$21 \times 30 = 630$
Add: $21 + 630 = 651$

Step11: Multiply by ones digit (2e)

Multiply 30 by 0:
$30 \times 0 = 0$
Multiply 30 by 30:
$30 \times 30 = 900$
Add: $0 + 900 = 900$

Step12: Multiply by ones digit (2f)

Multiply 14 by 0:
$14 \times 0 = 0$
Multiply 14 by 10:
$14 \times 10 = 140$
Add: $0 + 140 = 140$

Step13: Multiply by ones digit (3a)

Multiply 22 by 4:
$22 \times 4 = 88$
Multiply 22 by 40:
$22 \times 40 = 880$
Add: $88 + 880 = 968$

Step14: Multiply by ones digit (3b)

Multiply 14 by 0:
$14 \times 0 = 0$
Multiply 14 by 20:
$14 \times 20 = 280$
Add: $0 + 280 = 280$

Step15: Multiply by ones digit (3c)

Multiply 40 by 2:
$40 \times 2 = 80$
Multiply 40 by 10:
$40 \times 10 = 400$
Add: $80 + 400 = 480$

Step16: Multiply by ones digit (3d)

Multiply 90 by 0:
$90 \times 0 = 0$
Multiply 90 by 10:
$90 \times 10 = 900$
Add: $0 + 900 = 900$

Step17: Multiply by ones digit (3e)

Multiply 13 by 3:
$13 \times 3 = 39$
Multiply 13 by 10:
$13 \times 10 = 130$
Add: $39 + 130 = 169$

Step18: Multiply by ones digit (3f)

Multiply 30 by 1:
$30 \times 1 = 30$
Multiply 30 by 10:
$30 \times 10 = 300$
Add: $30 + 300 = 330$

Step19: Multiply by ones digit (4a)

Multiply 70 by 1:
$70 \times 1 = 70$
Multiply 70 by 10:
$70 \times 10 = 700$
Add: $70 + 700 = 770$

Step20: Multiply by ones digit (4b)

Multiply 12 by 1:
$12 \times 1 = 12$
Multiply 12 by 10:
$12 \times 10 = 120$
Add: $12 + 120 = 132$

Step21: Multiply by ones digit (4c)

Multiply 81 by 0:
$81 \times 0 = 0$
Multiply 81 by 10:
$81 \times 10 = 810$
Add: $0 + 810 = 810$

Step22: Multiply by ones digit (4d)

Multiply 24 by 2:
$24 \times 2 = 48$
Multiply 24 by 10:
$24 \times 10 = 240$
Add: $48 + 240 = 288$

Step23: Multiply by ones digit (4e)

Multiply 40 by 2:
$40 \times 2 = 80$
Multiply 40 by 20:
$40 \times 20 = 800$
Add: $80 + 800 = 880$

Answer:

1.
a. 726
b. 495
c. 800
d. 713
e. 156
f. 930

2.
a. 861
b. 640
c. 400
d. 651
e. 900
f. 140

3.
a. 968
b. 280
c. 480
d. 900
e. 169
f. 330

4.
a. 770
b. 132
c. 810
d. 288
e. 880