3 Digits
In the last article we learned the vertical and crosswise method for two digits. Today we look at the same method for three-digit numbers. It may seem difficult in the beginning but with practice we can master it.
Let us see the steps involved in a diagrammatic form.
Step 1: Multiply the units digits vertically.
Step 2: Multiply the units and the tens digits crosswise and add them.
Step 3: Multiply the three digits as shown in the figure and add them.
Step 4: Multiply the tens and the hundreds digits crosswise and add them.
Step 5: Multiply the hundreds digits vertically.
Example 1:
123 x 112
Step 1: Multiply the units digits vertically
3 x 2 = 6
Step 2: Multiply the units and the tens digits crosswise and add
(2 x 2) + (1 x 3) = 7
Step 3: Multiply the three digits as shown in the figure and add
(1 x 2) + (3 x 1) + (2 x 1) = 7
Step 4: Multiply the tens and the hundreds digits crosswise and add
(1 x 1) + (2 x 1) = 3
Step 5: Multiply the hundreds digits vertically
1 x 1 = 1
Answer: 13776
Example 2: 145 x 213
Step 1: Multiply the units digits vertically
5 x 3 = 15
Step 2: Multiply the units and the tens digits crosswise and add
(4 x 3) + (5 x 1) = 17
Step 3: Multiply the three digits as shown in the figure and add
(1 x 3) + (5 x 2) + (4 x 1) = 17
Step 4: Multiply the tens and the hundreds digits crosswise and add
(1 x 1) + (4 x 2) = 9
Step 5: Multiply the hundreds digits vertically
1 x 2 = 2
(For every double-digit number put down the right hand digit in the answer and carry the other over)
Answer: 30885