Since 1 Indian Rupee is equal to 3.888219775485609 Sri Lankan Rupees, we could say that n Indian Rupees are equal to 3.888219775485609 times n Sri Lankan Rupees. In other words, we could use the following formula:
Sri Lankan Rupees = Indian Rupees x 3.888219775485609
For example, let's say that we want to convert 2.0 Indian Rupees to Sri Lankan Rupees. Then, we just replace Indian Rupees in the abovementioned formula with 2.0:
Sri Lankan Rupees = 2.0 x 3.888219775485609
That is, 2.0 Indian Rupees are equal to 7.776439550971218 Sri Lankan Rupees.