SOLUTION: How many four-digit numbers can be formed using the digits 1,2,3,4,5,6,7,8, and 9. a) if repetition is allowed? b) if repetition is not allowed? c) How many of 4 digits numbers

Question 1072909: How many four-digit numbers can be formed using the digits 1,2,3,4,5,6,7,8, and 9.
a) if repetition is allowed?
b) if repetition is not allowed?
c) How many of 4 digits numbers in (a) are greater than 6000?

Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!
a)
b)
c) Look at numbers starting in 6,

Same number for numbers starting in 7,8, and 9.
So there are 4 sets of 9*9*9.

RELATED QUESTIONS
How many four-digit numbers can be formed using the digits 1, 2, 3, 4, 5, 6, if the... (answered by mccravyedwin,Edwin McCravy,ikleyn)

How many 4-digit numbers can be formed using the digits 1, 2, 3, 4, 5, 6, 7 if... (answered by robertb)

How many different 4-digit even numbers can be formed from the digits 1,3,5,6,8, and 9 if (answered by ikleyn)

Given the digits 1,2,4,6,8 and 9, how many four - digit numbers can be formed if... (answered by ikleyn)

1. How many different 4-digit numbers can be formed from the digits 2, 3, 4, 5, 6, 7, and (answered by Alan3354)

Four-Digit Number. How many four-digit numbers can be formed using the digits 0, 1, 2, 3, (answered by MathLover1,jilalbenkad)

How many 4-digit odd numbers can be formed from the digits 1, 3, 5, 6, 8, and 9 if... (answered by math_helper)

how many 3-digit numbers can be made with the digit 1,2,3,4,5,6,7 if repetition is... (answered by ikleyn)

How many 5-digit numbers can be formed using the digits 1, 2, 3, 4, 5, 6 and 7 if... (answered by edjones)