Math

XLII, XLV, XXV, And XCLX Roman Numerals In Numbers

In this article, I will show how to convert XLII, XLV, XXV, and XCLX Roman Numerals in numbers. I have done some examples and I made it clear that these are the numbers that were used in ancient Rome, which are in base ten and comprise of the Latin alphabet (I, V, X, L, C, D, and M).

Before I proceed, I would like to take you through the basic rule, this will help your understanding as I solve the examples above.

Basic Rule

  • If a bigger letter precedes or comes before a smaller letter, the letters are added. For example: LV = 50 + 5 = 55
  • If a smaller letter precedes a bigger letter, the letters are subtracted. For example XC = 100 – 10 = 90
  • If a letter is repeated 2 or 3 times, they are added. For example: XXX = X + X + X = 10 + 10 + 10 = 30
  • The same letter cannot be used more than three times in succession.

XLII

XLII = XL + I + I (note XL = 50 – 10 = 40)

The reason why I put XL together is that a smaller number comes before a bigger number

XLII = 40 + 1 + 1 = 42

XLV

XLV = XL + V (note XL is 40 and V is 5)

XLV = 40 + 5 = 45

XXV

XXV = X + X + V = 10 + 10 + 5 = 25

XCLX

This is not a valid Roman Numeral because the numerals L and x may not follow a group of numerals in subtractive notation i.e. L and X can’t follow XC

In conclusion, the tabular representation will be shown below.

Roman NumeralsNumber
XLII42
XLV45
XXV25
XCLXNot valid

Read: XXXVII, CXXXIX, XXIX, XXVI, LXXX, XL, XI Roman Numerals

Bolarinwa Olajire

A tutor with a demonstrated history of working in the education industry. Skilled in analytical skills. Strong education professional with a M. SC focused in condensed matter. You can follow me on Twitter by clicking on the icon below to ask questions.

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