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Trailing binary zeros of 142 factorial

Question

When 142!142! is written in base 22, how many zeros does it end with?

Short answer

138138. The count equals the exponent of 22 in 142!142!. By Legendre's formula, repeatedly halve and round down: the floors 71,35,17,8,4,2,171,35,17,8,4,2,1 add to 138138.

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