Assuming a 5 digit number cannot start with 0, ie it must be at least 10,000, then there are 96 possible numbers:
there are 4 choices for the first digit,
leaving a choice of 4 for the second digit for each of the choices for the first digit,
leaving a choice of 3 for the third digit for each of the choices for the first two digits,
leaving a choice of 2 for the fourth digit for each of the choices for the first three digits,
leaving a choice of 1 for the fifth (and final) digit for each of the choices for the first four digits,
Making a total number of choices 4 x 4 x 3 x 2 x 1 = 96
# 230 # 203 # 320 # 302
if the repetition is allowed the there is 6*6*6 possible ways = 216
With repetition, 94 = 6561. Without repetition, 9*8*7*6 = 3024.
There are 2000 such numbers.
Assuming you meant the largest 3 digit number without repetition:Largest 4 digit without repetition = 9876Largest 3 digit = 987⇒ difference = 9876 - 987 = 8889
I take it that you want to make three digits numbers with 8,7,3, and 6 without repetition. The first digit cane be selected from among 4 digits, the second from 3 digits, the third digit from 2, hence the number of three digit numbers that can be formed without repetition is 4 x 3 x 2 = 24
Six (6)
There are 600 such numbers.
There are 504 such numbers.
If repetition is allowed . . . . . 343 If repetition is not allowed . . . . . 210
9*8*7 = 504 of them.
3*2*1 = 6 of them.
64 if repetition is allowed.24 if repetition is not allowed.
9999 - 102 = 9897
1
# 230 # 203 # 320 # 302
9999-1023 = 8976