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What is the remainder when 1! + 2! + 3! + 4! + 5! ............+ 95! is divided by 9?

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Correct Answer - Option 1 : 0

Given:

Expression is 1! + 2!  + 3! + 4! + 5! ......… + 95!

Calculation:

Here, given expression is 1! + 2!  + 3! + 4! + 5! .........… + 95!

1! = 1

2! = 2 × 1 = 2

3! = 3 × 2 × 1 = 6

4! = 4 × 3 × 2 × 1 = 24

5! = 5 × 4 × 3 × 2 × 1 = 120

6! = 6 × 5 × 4 × 3 × 2 × 1 = 720

So, 6! It is divisible by 9.

7! = 7 × 6 × 5 × 4 × 3 × 2 × 1 = 5040

So, 7! It is divisible by 9.

Similarly, every term greater than 6! In the given expression will be divisible by 9.

So, the sum of terms that are not divisible by 9 is

1! + 2! + 3! + 4! + 5! = 1 + 2 + 6 + 24 + 120 = 153

So, the remainder of 153 when divided by 9 will be 0.

∴ The remainder when 1! + 2!  + 3! + … + 95!  is divided by 9 is 0.

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