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Factorial Trailing Zeros Calculator

Trailing zeros in n! = floor(n/5) + floor(n/25) + …

Counts the number of trailing zeros in n factorial using the standard Legendre formula based on factors of 5.

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Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

Trailing zeros = ⌊n/5⌋ + ⌊n/25⌋ + ⌊n/125⌋ + …

In depth

Counts the number of trailing zeros in n factorial using the standard Legendre formula based on factors of 5.