Question

How many Six-digit telephone numbers can be formed by using 10 distinct digits
a) $10^{8}$
b) $6^{10}$
c) 10$C_{9}$
d) 10$P_{6}$

Answer 1

use the rule f(r) =n^r

10^6

Answer 2

Answer:

None of the mentioned options are correct.

Correct answer is 900000

Step-by-step explanation:

For a 6 digit number to form,

Digit in highest place have 9 options. (0 can not be first digit)

after that, remaining 5 positions can be filled by 10 options each.

Each of next digit can have any of the 10 digits.

Total numbers possible = multiplication of choices for each position.

Hence total possible 6 digit numbers = 9*10*10*10*10*10

= 900000.