Question

The number of 3-digit numbers, formed using the digits 2, 3, 4, 5 and 7, when the repetition of digits is not allowed, and which are not divisible by 3, is equal to ______.

Answer 1

Correct answer is : 36 

2, 3, 4, 5, 7

total number of three digit numbers not divisible by 3 will be formed by using the digits

(4, 5, 7) 

(3, 4, 7) 

(2, 5, 7) 

(2, 4, 7) 

(2, 4, 5) 

(2, 3, 5)

number of ways \(=6 \times 3 !=36\)