UPSC 2016 CDS II Math Paper

Number of rupees saved by the boy in 10 days =4.65×10=₹46.50, which is not exact number of rupees
Number of rupees saved by the boy in 20 days =4.65×20=Rs93.00,which is exact number of rupees
Thus, the least number of days in which the boy will be able to save an exact number of rupees is 20.