It's 2019 ! 2019!

Number Theory Level 3

What is the last non zero digit of 2019 ! 2019! from the left?

Notation: ! ! denotes the factorial notation , For example: 8 ! = 1 × 2 × 3 × 4 × 5 × 6 × 7 × 8 8! =1 \times 2 \times 3 \times 4 \times 5 \times 6 \times 7 \times 8 .

4 8 6 2 3

Mr. India by Mr. India , 17, India

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1 solution

Brute force. The result is a 5799 digit number.

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What is 'brute force'?

Mr. India - 2 years, 1 month ago

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Actually calculating the exact value of 2019!

Joshua Lowrance - 2 years, 1 month ago

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Is there no other way?

Mr. India - 2 years, 1 month ago

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@Mr. India – There are other methods. They are about as much work.

A Former Brilliant Member - 2 years ago

I computed the entire 2019! value and then searched and found the last non-zero digit.

A Former Brilliant Member - 2 years ago

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