5 digit telephone numbers having at least one of their digits repeated is
= total possible 5 digit telephone numbers - 5 digit telephone numbers without any digit being repeated.
=(10*10*10*10*10)-(10*9*8*7*6)
=100000-30240
=69760
763920
6561
500
7
It is 120 if the digits cannot be repeated.
763920
98,764
If the digits may not be repeated, there are 6x5x4x3x2x1 = 720 numbers, If digits can be repeated, the answer is 6x6x6x6x6x6 = 46,656 numbers If zero is ong the available digits but is excluded from the first place. 5x6x6x6x6x6=38,880 numbers
757
It is possible to create a 3-digit number, without repeated digits so the probability is 1.
There are 5*4*3 = 60 such numbers.
6561
24
500
7
With repeated digits, 43 = 64 Without repeated digits, 4*3*2 = 24
9x9x8x7x6x5x4x3 =1632960