Question
A number when divided by 18 leaves a remainder 7. The same number when divided by 12 leaves a remainder n. How many values can n take?
CAT 2021
Solution
Correct option is
(A)
Explanatory Answer :
18a+7=12b+n
18a+7= 25,43,61,79
check remainder in all these cases it is following pattern of either 1 or 7
other method
18a+7=(12+6)a+7=12a+(6a+7)
so we can say no when divided by 12 gives remainder as 6a+7 i.e. 13,19,25 as remainder while dividing by 12 can't be greater than 12 hence 1,7.