In Roman numeration, if a symbol is repeated, its value is multiplied as many times as it occurs.
Idea: When the same Roman symbol is written again and again (side by side), we add its value each time.
This is the same as “multiply by how many times it appears”.
Example 1 (I means 1):
\( I + I + I \)
\( = 1 + 1 + 1 \)
\( = 3 \)
So \( III = 3 \). This is the same as \( 3 \times I \).
Example 2 (X means 10):
\( X + X \)
\( = 10 + 10 \)
\( = 20 \)
So \( XX = 20 = 2 \times X \).
\( XXX = X + X + X \)
\( = 10 + 10 + 10 \)
\( = 30 = 3 \times X \).
Example 3 (C means 100):
\( CC = 100 + 100 = 200 = 2 \times C \).
Note for beginners: In standard Roman numerals, you usually do not repeat a symbol more than three times in a row, and the symbols V, L, and D are not repeated.