Question

124:64::123:27::126:216::121:?
According to mental ability

Answer 1

124-123=1
64=4^3
27=3^3
126-121=5
216=6^3
1=1^3

Answer 2

unit's digit of 124 is 4,so the cube of 4 ie 64 is it's pair.
similarly,unit's digit of 123 is 3,so the cube of 3 ie 27 is it's pair.
similarly, unit's digit of 121 is 1,therefore cube of 1 is the answer