The number of 5-digit telephone numbers having atleast one of their digits repeated is
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
6 views
1 Answers
Answer is (D)
Total number of telephone numbers when there is no restriction = 105 Also number of telephone numbers having all digits different = 10P5 Required number of ways = 105 – 10P5 = 1000000 -10x9x8x7x6 = 1000000 - 30240 = 69760
6 views
Answered