Basic arithmetic 3
12
60
50
38
120
110
B
A
d
Figure 1.1
1.3 Revision of multiplication and
division
You can probably already multiply two numbers
together and divide one number by another. However, if
you need a revision then the following worked problems
should be helpful.
Problem 7. Determine 86 × 7
H T U
8 6
×
7
6 0 2
4
(i) 7 × 6 = 42. Place the 2 in the units (U) column
and ‘carry’ the 4 into the tens (T) column.
(ii) 7 × 8 = 56; 56 + 4 (carried) = 60. Place the 0 in
the tens column and the 6 in the hundreds (H)
column.
Hence, 86 × 7 = 602
A good grasp of multiplication tables is needed when
multiplying such numbers; a reminder of the multiplication table up to 12 × 12 is shown below. Confidence
with handling numbers will be greatly improved if this
table is memorized.
Problem 8. Determine 764 × 38
7 6 4
× 3 8
6 1 1 2
2 2 9 2 0
2 9 0 3 2
Multiplication table
×
2
3
4
5
6
7
8
9
10
11
12
2
4
6
8
10
12
14
16
18
20
22
24
3
6
9
12
15
18
21
24
27
30
33
36
4
8
12
16
20
24
28
32
36
40
44
48
5
10
15
20
25
30
35
40
45
50
55
60
6
12
18
24
30
36
42
48
54
60
66
72
7
14
21
28
35
42
49
56
63
70
77
84
8
16
24
32
40
48
56
64
72
80
88
96
9
18
27
36
45
54
63
72
81
90
99
108
10
20
30
40
50
60
70
80
90
100
110
120
11
22
33
44
55
66
77
88
99
110
121
132
12
24
36
48
60
72
84
96
108
120
132
144