Question

A seven-digit number comprises of only 2's and 3's. How many of these are multiples `of 12?
(A)1
(B)11
(C)21
(D)44

Answer 1

Answer:

Step-by-step explanation:

a number is divisible by 12 only if it is divisible by 3 and 4.

and a number is divisible by 3 it it's digits are added and the result is divisible by 3.  

a number is divisible by 4 if it;s last two digits is divisible by 4

so 2233332 if we rake this number 2+2+3+3+3+3+2= 18 and last digit is 32 means number is divisible by both 3 and 4 so divisible by 12.

note here that last cannot be 3 because then that number will not be divisible by 4. and the last two digits will always be 32 to be divisible by 4.

so 22333 32 . fix 32 in the last

use combination 5!/2!*3!= 10

2nd we can use also 2222232 . only 1 combination possible here. so answer is 11.

Answer 2

Answer:

Step-by-step explanation: