How many 5-digit telephone numbers can be constructed using the digits 0 to 9 if each number starts with 67 and no digit appears more than once?
Answers
Answered by
67
There are 10 digits from 0 to 9
I place after 67 can be filled in 8 ways.
II place after 67 can be filled in 7 ways.
III place after 67 can be filled in 6 ways.
∴ No of telephone numbers that can be constructed.
⇒8×7×6
⇒336
Answered by
37
Hey ya frnd....here is ur answer!!ʕ•ٹ•ʔ
✌️__________✌️
●There r 10 digits 0 to 9
and in the 5 digit telephone no. 1st and 2nd digits are fixed, it means now we have find the total no. of combination of 3 digits with 8 no.s 0 to 9(excluding 6 n'7)
●The total no. of combinations of 3 digit no. using 8 numbers = 8×7×6
∆Formula used ([ n! ÷ (n-r)!])
◆8×7×6 = 336
✌️__________✌️
I hope this will help u...☺️^-^☺️
✌️__________✌️
●There r 10 digits 0 to 9
and in the 5 digit telephone no. 1st and 2nd digits are fixed, it means now we have find the total no. of combination of 3 digits with 8 no.s 0 to 9(excluding 6 n'7)
●The total no. of combinations of 3 digit no. using 8 numbers = 8×7×6
∆Formula used ([ n! ÷ (n-r)!])
◆8×7×6 = 336
✌️__________✌️
I hope this will help u...☺️^-^☺️
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