0
Since the repetition of digits is not allowed then the number of 7 digit numbers formed = 9 x 9 x 8 x 7 x 6 x 5 x 4 = 544320
Explanation:
The first digit of the number can't be 0 so we have 9 digits to choose from.
And the remaining last places(here 6) can be filled by using the remaining 9 digits i.e. 9P6 = 9!/(9-6)! = 9 x 8 x 7 x 6 x 5 x 4
So, the result is 9 x 9P6 .
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How many different 3 digit house numbers could be made using numerals 4 7 8?
Six.
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210
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How many numbers can you make from 650271 without repeating a digit?
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