Roman Calc

The result of all calculations will be displayed as a roman number.  Tap the Convert button to convert Roman to Arabic and visa versa.  Roman Number entries will automatically display in the correct format.  For example IIII will display as IV.  You can turn off the autocorrect feature in the preferences.  Numbers smaller than 1/12 and larger than 1 billion will not display.  Roman Fractions will trucate to the nearest 1/12th.

The Roman Calculator comes with four background styles and five button styles.  The styles can be set in the preferences or can changed with a swipe motion.  Left swipe will change the background and right swipe with change the button style.   A background can be selected from your photo library.

Roman Numbers:

Roman numerals are based on seven symbols: a stroke (identified with the letter I) for a unit, a chevron (identified with the letter V) for a five, a cross-stroke (identified with the letter X) for a ten, a C (identified as an abbreviation of Centum) for a hundred, etc.:

I = 1 (one) (unus)

V = 5 (five) (quinque)

X = 10 (ten) (decem)

L = 50 (fifty) (quinquaginta)

C = 100 (one hundred) (centum)

D = 500 (five hundred) (quingenti)

M = 1,000 (one thousand) (mille)

Large Numbers:

For large numbers (4,000 and above), parentheses are placed around it, to indicate multiplication by 1,000.  The “()” button will put parentheses around the last roman digit entered.  For numbers larger than 1 million, Romans repeated the (M).  To save display space, Roman Calc truncates the (M)s for numbers between 5 million and 1 billion.  Example, large roman numbers:

(V) = five thousand

(X) = ten thousand

(L) = fifty thousand

(C) = one hundred thousand

(D) = five hundred thousand

(M) = one million

13(M)…(C)(C)(L)(V)MDCCCLXXIV = 13,256,874


Though the Romans used a decimal system for whole numbers, reflecting how they counted in Latin, they used a duodecimal system for fractions, because the divisibility of twelve (12 = 3 × 2 × 2) makes it easier to handle the common fractions of 1/3 and 1/4 than does a system based on ten (10 = 2 × 5). On coins, many of which had values that were duodecimal fractions of the unit as, they used a tally-like notational system based on twelfths and halves. A dot • indicated an uncia “twelfth”, the source of the English words inch and ounce; dots were repeated for fractions up to five twelfths. Six twelfths (one half) was abbreviated as the letter S for semis “half”. Uncia dots were added to S for fractions from seven to eleven twelfths, just as tallies were added to V for whole numbers from six to nine.


In general, the number zero did not have its own Roman numeral, but a primitive form (nulla) was known by medieval computists (responsible for calculating the date of Easter). They included zero (via the Latin word nulla meaning “none”) as one of nineteen epacts, or the age of the moon on March 22. The first three epacts were nulla, xi, and xxii (written in minuscule or lower case). The first known computist to use zero was Dionysius Exiguus in 525. Only one instance of a Roman numeral for zero is known. About 725, Bede or one of his colleagues used the letter N, the initial of nulla, in a table of epacts, all written in Roman numerals.

Based on Wikipedia, the free encyclopedia.

Frequently Asked Questions

Q:  What is roman mean?

A:  Roman Numeral S is the symbol for 1/2.

Q:  Are the trigonometric functions based on degrees or radian?

A:  Use radians for trigonometric functions.  2π radians = 360 degrees.

Q:  How do I change backgrounds and buttons?

A:  From the home screen tap the setting icon: 1. Tap RomanCalc, 2. Tap Background Style, 3. Choose a style

Tap RomanCalc

Tap Background Style

Choose a Style

A:  Also Swipe left to change backgrounds and swipe right to change button styles.

Q:  How do I set the background as a picture from my photo library?

A:  Flip to the help screen and tap the camera.  Then tap a picture from one of your photo albums.

Roman Calc Version History

  •   1.0  –  2 Feb 2011
    •     Initial Release
  •   1.1  –  Not Released
    •     Added scientific notation
    •     Fixed multiple leading zeros (For example:  0001)
  •   1.2  –  27 Feb 2011
    •     Fixed crash on large negative numbers
    •     Added new backgrounds
    •     Added new functions
    •     Added display for roman numbers between 5 million and 1 billion
    •     Added support for operation order
  •     1.3  –  13 Mar 2011
    •     Formatted help page
    •     Fixed retain error (App would crash on +=+=+= button combination)
    •     Added backwards compatible to iOS 3.2
  •     1.4  –  8 Apr 2011
    •     Added localization support for Romanian
    •     Added preference to toggle autocorrect
    •     Added persistence from landscape to portrait display
    •     Fixed IMM to equal 1999 not 1979
  •     2.0  –  17 Jun 2011
    •     Added localization support for French, Spanish, and German
    •     Added preference for button style
    •     Added swipe to change button/background styles
    •     Fixed persistence between rotations
    •     Animated rotation of buttons
    •     Added help in landscape view
  •     2.1  –  23 Jun 2011
    •     Fixed preference for background style
  •     2.2  –  3 Aug 2011
    •     Added photo library as background style
  •     2.3 – 17 Oct 2012
    •    Fixed background on 4 inch screens
  •     2.4 – 6 Nov 2012
    • Expand background and buttons for 4 inch screen.
  • 2.5 – 17 Nov 2012
    • Update instructions
  • 2.6 – 5 Dec 2012
    • Fixed adding background photos on iPad
  • 7.0 – 17 Sep 2013
    • Update for iOS 7.0
    • Note version numbering now inline with iOS numbering
  • 7.0.1 – 3 Oct 2013
    • Fixed overlap on status bar on flip view.
  • 7.0.2 – 8 Oct 2013
    • Fixed iPad to display buttons correctly
  • 7.0.3 – 20 Nov 2013
    • Update screen shots

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