Question:
A child has three plastic toys bearing the digits 3, 3, 5 respectively. How many 3 - digit numbers can he make using them?
Solution:
To find: number of 3 digit numbers he can make
If all were distinct, he could have made $3 !=6$ numbers
But 2 number are the same
So the number of possibilities $=\frac{3 !}{2 !}=\frac{6}{2}=3$
He can make 3 three - digit numbers using them