Question

31k2 is divisible by 6 find k

Answer 1

the divisibility rule for 2 is the last digit should be even number
so the last digit is 2..and it is even number...so it is divisible by 2
the divisibility rule for 3 is sum of all digits should be divisible by 3
so by trail and error method
3+1+1+2=7 [not divisible]
3+1+2+2=8 [not divisible]
3+1+3+2=9    [divisible]
3+1+4+2=10[not divisible]
3+1+5+2=11[not divisible]
3+1+6+2=12   [divisible]
3+1+7+2=13[not divisible]
3+1+8+2=14[not divisible]
3+1+9+2=15    [divisible]
so the value of k may be 3 or 6 or 9