Question

How many six digit number can be made from the digits 1, 1, 1, 2, 2, 3?

Answer 1

The permutation of all digits is $6!$, but we don't differentiate the same digits, so we divide it by the number of permutations of 1's ($3!$) and 2's ($2!$)

$\dfrac{6!}{3!2!}=\dfrac{4\cdot5\cdot6}{2}=60$