Problems Based On Multiplication

November 4th, 2009

TYPE 1: Multiplying by 12

Consider

Example 1 :12 X 7

Step 1: Multiply the 1 of the 12 by the
number we are multiplying by, in this case 7. So 1 X 7 = 7.

Step 2: Multiply this 7 by 10 giving 70.

Step 3: Now multiply the 7 by the 2 of twelve giving 14. Add this to 70 giving 84.

Therefore 7 X 12 = 84

Example 2: 17 X 12

Step 1: Multiply the 1 of the 12 by the
number we are multiplying by, in this case 17. So 1 X 7 =1 7.

Step 2: Multiply this 17 by 10 giving 170.

Step 3: Now multiply the 17 by the 2 of twelve giving 34. Add this to 170 giving 204.

Therefore 17 X 12 = 204

TYPE 2: Using VERTICALLY AND CROSSWISE you do not need to the multiplication tables beyond 5 X 5.

Example 1: Suppose for 8 x 7

8 is 2 below 10 and

7 is 3 below 10.

This can be written as

8         2

X

7       3

5       6

Step 1: You subtract crosswise 8-3 or 7 – 2 to get 5,to get the first figure of the answer.

Step 2: You multiply vertically: 2 x 3 to get 6, the last figure of the answer.

Step 3: Thus, the answer is 56.

Example 2: Suppose for 7 x 6

7 is 3 below 10 and

6 is 4 below 10.

This can be written as

7         3

X

6       4

3          12

Step 1: You subtract crosswise 6-3 or 7 – 4 to get 3,to get the first figure of the answer.

Step 2: You multiply vertically: 4 x 3 to get 12, the last figure of the answer. There is a carry: the 1 in the 12 goes over to make 3 into 4.

Step 3: Thus, the answer is 42.

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