Multiplication of numbers with a series of 1’s

This method is so obvious that it needs no further elaboration.

Let us begin with the multiplier 11.

(Q) Multiply 32 by 11.

• 32 × 11

First, we write the right-hand digit, 2, as it is. (Answer = _______2).
Next, we add 2 to the number on the left, 3, and write 5. (Answer = ______52).
Last, we write the left-hand digit 3 as it is.

Thus, the answer is 352.

(Q) Multiply 652 by 11.

The logic of two-digit numbers can be expanded to higher numbers. In the given example, we have to multiply 652 by 11.

• We write down the last digit of the answer as 2. (Answer = ____2).
• Next, we add 2 to 5 and make it 7. (Answer = ____72).
• Next, we add 5 to 6 and make it 11. We write down 1 and carry over 1. (Answer is ____172).
• Last, we take 6 and add the one carried over to make it 7. (Final answer is 7172.).

Since the multiplier 11 has two 1’s, we add a maximum of two digits at a time. When the multiplier is 111, we will add a maximum of three digits at a time because the multiplier 111 has three digits. When the multiplier is 1111, we will add a maximum of four digits at a time since the multiplier 1111 has four digits.