Question

Write the last 4 digits of a telephone number (each digit MUST be different--ex. 5237). List all the 4-digit numbers you can make using those 4 digits.

Answer 1

5040

Explanation:

All the possible Numbers that can be placed in the last for places =0,1,2,3,4,5,6,7,8,9

If all the digits have be different , then

= 10 x 9 x 8 x 7

= 90 x 56

= 5040 are total no. of 4-digit numbers can be made using those 4 digits.