Concept used: The remainder can be multiplied in the same way as the actual number when divided by any other number Ex-
52/4=(5×5)/4=(1×1)/4=1/4 ,
Remainder = 1 Calculation: 45 is divided by 15 ⇒45/[15 ⇒(42×42×4)/15 ⇒(16×16×4)/15 ⇒(1×1×4)/15 ----(When 16 and 4 is divided by 15 then it gives 1 and 4 as remainder respectively) ⇒4/15 ∴ The remainder is 4