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# Puzzles

## Archive

Show me a random puzzle
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## 10 December

How many zeros does 1000! (ie 1000 × 999 × 998 × ... × 1) end with?

## Factorial pattern

$$1\times1!=2!-1$$ $$1\times1!+2\times2!=3!-1$$ $$1\times1!+2\times2!+3\times3!=4!-1$$
Does this pattern continue?

## 17 December

In March, I posted the puzzle One Hundred Factorial, which asked how many zeros 100! ends with.
What is the smallest number, n, such that n! ends with 50 zeros?

## One hundred factorial

How many zeros does $$100!$$ end with?