Page 192 - Start Up Mathematics_3

(c) Multiplying any number by 12

Let’s learn how to multiply any number by 12 with the help of an example.

Example 7: Find 1432 × 12.

Solution: Step 1: Write the first digit of 1432 as it is.

1 → 1st digit of the answer.

Step 2: Multiply 1 by 2 and add the next digit, i.e., 4.
1 × 2 + 4 = 2 + 4 = 6

Step 3: Now multiply 4 by 2 and add the next digit, i.e., 3.

4 × 2 + 3 = 8 + 3 = 1 1 → 3rd digit of the answer.

Since 11 is a two-digit number, keep one 1 and carry 1 to
step 2 and add it to 6.
1 + 6 = 7 → 2nd digit of the answer.

Step 4: Multiply 3 by 2 and add the next digit, i.e., 2.

3 × 2 + 2 = 6 + 2 = 8 → 4th digit of the answer.

Step 5: Multiply 2 by 2. [As there are no more digits, we do not add
any digit in step 5.]

2 × 2 = 4 → last digit of the answer.
So, 1432 × 12 = 17184.

1 4 3 2 × 1 2

1 (1 × 2 + 4) (4 × 2 + 3) (3 × 2 + 2) 2 × 2

↓ ↓ ↓ ↓ ↓
1st digit 2nd digit 3rd digit 4th digit last digit

↓ ↓ ↓ ↓ ↓
1 +6 1 1 8 4

7
Try these: 235 × 12, 1064 × 12, 319 × 12

184
184