Multiply 999 by 5 in 2 seconds

You can multiply 999 by 5 in 2 seconds or less using this math trick.

999

Step 1

Multiply 9 by 5 to get 45.

Step 2

Leave some space between 4 and 5: 4     5

Step 3

Put 99 between 4 and 5

4995

999 by 5 = 4995

Was that easy? I bet it was!

 Let us then try another example with more 9s.

Multiply 9999999 by 5

9999999 × 5 = ?

Step 1

Multiply 9 by 5 to get 45.

Step 2

Leave some space between 4 and 5. This time you may have to leave more space since you have many 9s to put between 4 and 5: 4                5

Step 3

Put 999999 between 4 and 5

49999995

9999999 by 5 = 49999995

Another trick to multiply 999 by 5

The other trick that you can use to quickly perform the multiplication is to rewrite 999 as   

1000 - 1 since 999 = 1000 - 1. Then multiply (1000 - 1) by 5

(1000 - 1) × 5 = 1000 × 5 - 1 × 5 = 5000 - 5 = 4995