University:
Manchester University
Course:
MATH 105 | Basic Algebra
Academic year:

2024
Views:

164

Pages:

12
Author:

Clint W.

Roman Numerals Roman Numerals Past and Present • Romans used them for trading and commerce. • When Romans learned to write they needed a way to write their numbers. • Roman Numerals are still used today in many different ways. Roman vs. Arabic Numerals • Arabic Numerals are the numbers that we use today. – 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 • Roman Numerals are used today, but not in everyday writing. – I, V, X, L, C, D, M • Roman Numerals don’t have a symbol for zero. The Basics • • • • I – stands for one V – stands for five X – stands for ten L – stands for fifty • C – stands for one hundred • D – stands for five hundred • M – stands for one thousand The Rules for Writing Roman Numerals • The letters should be arranged from largest to smallest. – 1510 is written MDX, largest to smallest • Only powers of ten can be repeated. Don’t repeat a letter more than three times in a row. – 100 is written LL, not XXXXXXXXXX (too many repeats) Rules Continued • Numbers can be written using subtraction. A letter with a smaller value precedes one of the larger value. The smaller number is then subtracted from the larger number. – Only powers for ten (I, X, C, M) can be subtracted. – The smaller letter must be 1/5 or 1/10 the larger one. – The smaller letter must be either the first letter or preceded by a letter at least ten times greater than it. – CCXLIII=100+100+(50-10)+1+1+1=243 Practice • 515 = ? • 1005 = ? • 32 = ? • 9= ? Answers • 515 = DXV • 1005 = MV • 32 = XXXII • 9= IX Adding Roman Numerals • Write down the two numbers you are adding right next to each other • Rearrange the letters so they start with the largest and end with the smallest. • Then start combining similar letters. • Check you answer by adding the Arabic numbers. Now Let’s Try Adding Problem 1. 23 + 58 Answer to the Adding Problem Step Step Step Step Step Step Step Step Step 1. 2. 3. 4. 4. 5. 6. 7. 8. 23 + 58 XXIII + LVIII XXIIILVIII LXXVIIIIII IIIIII = VI LXXVVI VV = X LXXXI = 81 23 + 58 = 81 Roman Numeral Number I 1 V 5 X 10 L 50 C 100 D 500 M 1000 Roman Numerals Now you know the basics of Roman Numerals. You should be able to do simple problems that include Roman Numerals.