Topics
Roman Numerals
Number Work
Addition and Subtraction
Multiplication and Division
Fractions
Angles
Circles
Multiples and Factors
Decimal Fractions
- Decimal Fractions
- The Decimal Number System
- Concept of Tenths, Hundredths and Thousandths in Decimal
- Concept of Place Value
- Use of Decimal Fraction
- Writing Half, Quarter, Three-quarters and One and a Quarter in Decimal Form
- Addition of Decimal Fraction
- Subtraction of Decimal Fraction
- Decimals Used for Measurement
Measuring Time
Problems on Measurement
Perimeter and Area
Three Dimensional Objects and Nets
Pictographs
Patterns
Preparation for Algebra
Introduction to Roman Numerals
Roman Numbers: The Hindu-Arabic numeral system represents numbers using ten digits (0-9) with place value rules. Another way to write numbers is through the Roman numeral system, which uses symbols like I, V, X, L, C, D, and M.
This system was widely used in ancient Rome and is still seen today in clocks, book chapters, and historical names.
The Roman numerals I, II, III, IV, V, VI, VII, VIII, IX, and X denote 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10, respectively.
I | V | X | L | C | D | M |
1 | 5 | 10 | 50 | 100 | 500 | 1000 |
The rules for the system are:
- If a symbol is repeated, its value is added as many times as it occurs:
i.e., XX is 20 and XXX is 30. - A symbol is not repeated more than three times. But the symbols V, L, and D are never repeated.
- If a symbol of smaller value is written to the right of a symbol of greater value, its value gets added to the value of the greater symbol.
LXV = 50 + 10 + 5 = 65. - If a symbol of a smaller value is written to the left of a symbol of greater value, its value is subtracted from the value of the greater symbol.
XL = 50 – 10 = 40, XC = 100 – 10 = 90. - The symbols V, L, and D are never written to the left of a symbol of greater value, i.e., V, L, and D are never subtracted. The symbol I can be subtracted from V and X only. The symbol X can be subtracted from L, M, and C only.
Following these rules, we get
1 | I |
2 | II |
3 | III |
4 | IV |
5 | V |
6 | VI |
7 | VII |
8 | VIII |
9 | IX |
10 | X |
20 | XX |
30 | XXX |
40 | XL |
50 | L |
60 | LX |
70 | LXX |
80 | LXXX |
90 | XC |
100 | C |
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