GRE
$$\frac{100!}{99!}$$
$$\frac{ (100!-99!)}{98!}$$
$$\frac{(5!+6!)}{(6!+7!)}$$
$$\frac{1}{6}$$
20!+19!+18!
400(18!)
$$\frac{23!}{(11!*13!)}$$
$$\frac{23!}{(10!*14!)}$$
$$\frac{n!}{(\frac{n}{2})!}$$
2($$\frac{n}{2}$$)!
The probability that the number selected will have a units digit of 6
The probability that the number selected will have a tens digit of 6
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