Roman numerals: I (1), V (5), X (10), L(50), C( 100), D(500), M( 1000)?

Usage: believe in larger numbers, subtract left and add right. Now? The left side of the larger number is reduced; Yes, and then add.

For example, I is 1, then II is 2, IIX is 2 and 10, and the larger number is 10. If 2 is to the left of 10, it is simplified to 10-2=8, so IIX is 8.

In this question, IIL is 2 and 50, which is obviously 48.