Roman numerals Addition and subtraction

Learn roman numerals again in different way
Some more rules for addition and subtraction
Explanation, rules, examples, addition subtraction, Math fun, activity time, and much more

1. ROMAN NUMERALS
ADDITION & SUBTRACTION
Mathematics
Rajashri Bhairamadgi

2. Let’s recall…

3. Rules for subtraction
Rule 1:
Subtract only the values of letters I, X and C. Values of
V, L and D cannot be subtracted.

Example-
45= XLV [(50-10) + 5] 45 ≠ VL (50-5)

4. Rules for subtraction
Rule 2:
Subtract the value of only a single smaller numeral
from a single bigger numeral. In other words, you can
subtract only once from a numeral.

Example-
8= VIII (5+3) 8≠IIX(10-1-1)

5. Rules for subtraction
Rule 3:
Do not subtract a numeral from another numeral
which is more than 10 times greater, i.e. I can be
subtracted from V and X but not from L, C, D and M.
Similarly, X can be subtracted from L and C but not
from D, M and so on…..

Example-
9= IX (10-1)

6. Conversion of Roman to Hindu-Arabic numeral
Rule 1:
If a smaller number is to the left of a larger number,
subtract the value of the smaller number from the
larger number.

Example:
IX, I<X, IX=10-1=9
XL, X<L, XL=50-10=40

7. Conversion of Roman to Hindu-Arabic numeral
Rule 2:
If a smaller number is to the right of a larger number,
add the value of the smaller number to the large
number.

Example:
XI X>I XI=10+1=11

8. Conversion of Roman to Hindu-Arabic numeral
Rule 3:
If a number has more than two letters, add the value of
each letter to find the number

Example:

LXVIII LXVIII=50+10+5+1+1+1=68
CDI CDI= (CD)+I=(500-100)+1=401

9. Conversion of Hindu-Arabic to Roman numeral
1. Rule 1: To add, the smaller symbol is placed after
the bigger symbol
2. Rule 2: To subtract, the smaller symbol is placed
before the bigger symbol
3. Rule 3: I, X,C and M can be repeated only three
times in a row.
4. Rule 4: V, L and D cannot be repeated at all.

10. Conversion of Hindu-Arabic to Roman numeral
Examples:
1. 4= IV
2. 6=VI
3. 8=VIII
4. 9=IX
5. 40=XL
6. 90=XC
7. 67=LXVII
8. 52=LII
9. 95=XCV
10. 82=LXXXII

11. 1 to 100 Roman Numerals

12. Addition & Subtraction of Roman numerals
To add or subtract Roman numerals, follow
these steps-
1. Change the number into Hindu-Arabic
numbers
2. Add or subtract accordingly asked
3. Convert the answer into Roman numeral

13. Examples
1. XLV+ LXVIII
Solution:
XLV= 45
LXVIII=63

45+63=108=CVIII
XLV+ LXVIII=CVIII

14. Examples
2. CCXCVI-CLXXIV
Solution:
CCXCVI=296
CLXXIV=174

296-174=122=CXXII
CCXCVI-CLXXIV=CXXII

15. Trick to remember

16. Math Fun
How can half of XII be 7 ??


If we cut XII horizontally we get
VII i.e. 7

18. Activity time
! Design a birthday greeting with your birth
date marked on it in Roman numerals
! What letters of your name are used as
Roman numerals _______.
! Make a clock using cardboard and mark the
numbers 1 to 12 in Roman numerals

19. Thank you …. Happy learning