Quick Arithmetic - Multiply by 111

Multiply a number by 111 is pretty much the same as multiply a number by 11.

Multiply a 2 Digits Number by 111

Let's say we have a two digit number, and let's call it x. We can find the product of x with 111 easily by following the steps below:

  1. The product must be a 4 digits number.
  2. The first digit of the product is equal to the first digit of x, and the last digit of the product is equal to the last digit of x. For example, if x = 27. The first digit is 7, and the last digit is 2.
  3. The second and third digit of the product is equal to the sum of the 2 digits of x.
  4. If the sum of the digits is greater than 9, we add the tens digit to the next value place. For example, if x = 48.

Multiply a 3 Digits Number by 111

Multiply a 3 digit number by 111 is a little bit tricky. Let's say x = 324. As usual, we write the first and last digit of x as the first and last digit of the product.
The second digit of the product is equal to the sum of the first and second digit of x, 2 + 4 = 6.
Take NOTE that, the third digit of the product is equal to the sum of the 3 digits of x.
The forth digit of the product is equal to the sum of the last 2 digits of x.
 If the sum of the digits is greater than 9, we add the tens digit to the next value place. For example, if x = 675.

Multiply a 4 Digits Number by 111

Multiply a 4 digits number by 111 is the same as multiplying a 3 digits number by 111.

If the sum of the digits is greater than 9, we add the tens digit to the next value place.


Multiply a 5 Digits Number by 111

Here is the example of multiplying a 5 digits number by 111. Study it carefully to see whether you know how to do this.





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