Q. 365.0( 1 Vote )

# The number of 5-digit telephone numbers having atleast one of their digits repeated is

A. 90,000

B. 10,000

C. 30,240

D. 69,760

Answer :

Formula:- (i)^{n}P_{r}=

Total of of 5-digit telephone numbers=

If no number is repeated=^{10}P_{5}

The number of 5-digit telephone numbers having atleast one of their digits repeated is

=10^{5}-^{10}P_{5}

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