given the digits 0,1,2,3,4,5,6, and 7 find the number of possibilities in each category four digit numbers, odd three digit numbers and three digit numbers without repeating digits.
In each case we can assume that no whole number starts with a zero, and no repeating digits for all 3 cases.
number of 4 digits numbers = 6x6x5x4 = 720
number of 3 digit odd numbers, (must end in an odd) = 5x5x3 = 75
number of 3 digit numbers = 6x6x5 = 180