SOLUTION: 1) how many 6 digits telephone numbers are there that begin with 21 and that contain 4 or 3?

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Question 484752: 1) how many 6 digits telephone numbers are there that begin with 21 and that contain 4 or 3?
Answer by sudhanshu_kmr(1152) About Me  (Show Source):
You can put this solution on YOUR website!

number of possible numbers = 10^4 - 8^4 = 10000- 4096 = 5904