Answer: XCIX
This converts to the number 99
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Explanation:
The upper case letter i means the number 1 in roman numerals. The X represents 10. The C represents 100.
I = 1
X = 10
C = 100
When we form something like IX, we have the smaller digit first and then a larger digit next. Whenever this happens, we subtract
IX = 10-1 = 9
Similarly
XC = 100-10 = 90
So we can see that
IX + XC = 9 + 90 = 99
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Since XC is larger than IX, we list XC first when it comes to adding
In other words, we need to write IX+XC as XC+IX which collapses to XCIX
Placing XC next to IX without a plus sign implies the plus sign is there. This is effectively how roman numerals work (they are additive)
So,
XCIX = XC+IX = 90+9 = 99
Note how the XC takes care of the tens digit while IX takes care of the units digit.
