How many times does 24 divide into 100! (factorial)?
Solution
We first determine the number of times 2 and 3 divide into . Let \langle N\rangle_{n}nN). Since 2 only divides into even integers, \langle 100!\rangle_{2}=\langle 2 \cdot 4 \cdot 6 \cdots 100\rangle. Repeating this process, we find that \langle 100!\rangle_{2}=\left\langle 20^{50+25+12+6+3+1} \cdot 1\right\rangle_{2}=97. Now , so for each factor of 24 in 100! there needs to be three multiples of 2 and one multiple of 3 in 100!. Thus \langle 100!\rangle_{24}=\left(\left[\langle 100!\rangle_{2} / 3\right]+\langle 100!\rangle_{3}\right)=32[N]N$.
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