## Sunday, 30 October 2011

### CBSE Class VI ( 6th) Mathematics Chapter 1 : Knowing our Numbers -Roman Numerals System

The numbers 1,2,3,4,5,6,7,8,9, 10 etc, which we have been using  so far, are the numbers from the Hindu-Arabic numeral system . This is not the only system available. One of the early systems of writing numerals is the system of Roman numerals e.g. I, II, III, IV, V, VI, VII, VIII, IX, X etc. This system is still used in many places.
For example, we can see the use of Roman numerals in clocks; it is also used for classes in the school time table etc.

I, II, III, IV, V, VI, VII, VIII, IX, X denote 1,2,3,4,5,6,7,8,9 and 10 respectively. This is followed by XI for 11, XII for 12,... till XX for 20. Some more Roman numerals are :
 I V X L C D M 1 5 10 50 100 500 1000

### Hindu-Arabic numeral system and corresponding system of Roman numerals

 Hindu-Arabic numeral system = Roman numerals system Hindu-Arabic numeral system = Roman numerals system 1 = I 10 = X 2 = II 20 = XX 3 = III 30 = XXX 4 = IV 40 = XL 5 = V 50 = L 6 = IV 60 = LX 7 = VII 70 = LXX 8 = VIII 80 = LXXX 9 = IX 90 = XC 100 = C 500 = D 1000 = M

## The rules for writing numbers in the Roman system are :

(a) If a symbol is repeated, its value is added as many times as it occurs: i.e. II is equal 2, XX is 20 and XXX is 30.
(b) A symbol is not repeated more than three times. But the symbols V, L and D are never repeated.
(c) 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 greater symbol.
VI = 5 + 1 = 6, XII = 10 + 2 = 12
and LXV = 50 + 10 + 5 = 65
(d) If a symbol of smaller value is written to the left of a symbol of greater value, its value is subtracted from the value of the greater symbol.
IV = 5 – 1 = 4, IX = 10 – 1 = 9
XL= 50 – 10 = 40, XC = 100 – 10 = 90
(e) 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.

### Convert Hindu-Arabic Numbers from 1 to 100 into  Roman Numbers

 Hindu-Arabic numeral system = Roman numerals system 1 = I 2 = II 3 = III 4 = IV 5 = V 6 = VI 7 = VII 8 = VIII 9 = IX 10 = X 11 = XI 12 = XII 13 = XIII 14 = XIV 15 = XV 16 = XVI 17 = XVII 18 = XVIII 19 = XIX 20 = XX 21 = XXI 22 = XXII 23 = XIII 24 = XXIV 25 = XXV 26 = XXVI 27 = XXVII 28 = XXVIII 29 = XXIX 30 = XXX 31 = XXXI 32 = XXXII 33 = XXXIII 34 = XXXIV 35 = XXXV 36 = XXXVI 37 = XXXVI1 38 = XXXVI1I 39 = XXXIX 40 = XL 41 = XLI 42 = XLII 43 = XLIII 44 = XLIV 45 = XLV 46 = XLVI 47 = XLVII 48 = XLVIII 49 = XLIX 50 = L

 Hindu-Arabic numeral system = Roman numerals system 51 = LI 52 = LII 53 = LIII 54 = LIV 55 = LV 56 = LVI 57 = LVII 58 = LVIII 59 = LIX 60 = LX 61 = LXI 62 = LXII 63 = LXIII 64 = LXIV 65 = LXV 66 = LXVI 67 = LXVII 68 = LXVIII 69 = LXIX 70 = LXX 71 = LXXI 72 = LXXII 73 = LXXIII 74 = LXXIV 75 = LXXIV 76 = LXXV 77 = LXXVI 78 = LXXVII 79 = LXXVIII 80 = LXXX 81 = LXXXI 82 = LXXXII 83 = LXXXIII 84 = LXXXIV 85 = LXXXV 86 = LXXXVI 87 = LXXXVII 88 = LXXXVIII 89 = LXXXIX 90 = XC 91 = XCI 92 = XCII 93 = XCIII 94 = XCIV 95 = XCV 96 = XCVI 97 = XCVII 98 = XCVIII 99 = XCIX 100 = C
Question : Write the Roman number for the following Hindu-Arabic numbers : 289, 490, 758, 890, 995, 1115, 1419, 1899, 2534, 909, 1001