Suppose we want to form fivedigit numbers using the set of d

Suppose we want to form five-digit numbers using the set of digits {0,1,2,3}. For example. 30133 and 22301 are such numbers, but 03731 is not. How many such numbers are possible? There are five-digit numbers formed by using the digits {0,1,2,3}.

Solution

We can fill first spot by three digit {1, 2, 3} and other spots by 4 digits {0, 1, 2,3}

So total no. of digits = 3*4*4*4*4 =768