Solution - Roman numeral to integer

Read left to right.
If a smaller symbol comes before a larger one, treat them as one subtractive pair (for example, IX = 9).
Otherwise, each symbol stands alone.

For this input we get:

$$CD\left(400\right)+X\left(10\right)+X\left(10\right)+X\left(10\right)+V\left(5\right)+I\left(1\right)$$