from the digits 0,1,2,3,4,5,6,7,8,9 find the number of

Question

a) 4-digit numbers with repetition of digits
b) 4-digit numbers without repetition of digits
c) the number of odd 4-digit numbers with no repetition of digits
d) the number of even 4-digit numbers with no repetition of digits

Answer 1

We will be glad to criti9ue your thinking.

For (a), how many numbers are between 0 and 9999? Some have repeated digits.

These are not hard when you think about them