Question

How many 4-digit numbers can be formed from the digits 1, 2, 3, 4, 5, 6 and 7 which are divisible by 5 when none of the digits are repeated?.

Answer 1

Answer:

120 4-digit numbers.

Step-by-step explanation:

For the numbers to be divisible by 5 they must end in 5.

So the  total number of first 3 digits of the 4-digit number are given by the

number of permutations of 3 from the numbers 1,2,3,4,6 and 7 (6 digits)

= 6P3

=  6! / (6-3)!

= 6*5*4

= 120.