Removing one from eleven makes it ten and removing one from nine makes it ten

Removing one from eleven makes it ten and removing one from nine makes it ten

Can you solve this simple math riddle?

Removing one from eleven makes it ten and removing one from nine makes it ten.

How is this possible?

|

|

|

ANSWER

It is possible in Roman Numerals.
9 = IX
10 = X
11 = XI