Page 9 - SM Class 4 Inner.cdr

Comparing Numbers

We learn to compare numbers in previous class. Let us refresh our memory.

Rule 1 : The number containing more digits is the greater number.
as 794352 > 96895
because 794352 has 6 digits while 96895 has 5-digits.
Rule 2 : If number of digits are same, we compare the extreme left digits. Number
with greater value on extreme left digit is the greater number.
643215 > 519878
6 > 5
Rule 3 : If the extreme left digits of numbers are same, then compare second digit
from left in both numbers. Number with greater second left digit will be greater.
Continue this step until we come across unequal digits with corresponding places.

Examples : a. b.
L TTh Th H T O L TTh Th H T O L TTh Th H T O L TTh Th H T O
7 9 4 3 2 1 > 7 8 5 6 8 9 4 6 4 3 2 1 > 4 6 3 4 1 2

7 = 7 4 = 4
9 > 8 6 = 6
c.
L TTh Th H T O L TTh Th H T O 4 > 3
2 9 8 5 7 4 > 2 9 8 3 4 7
2 = 2

9 = 9
8 = 8

5 > 3
Forming Roman Numbers

In rules for formation of Roman-numerals system there is no symbol or digit for

zero. This system has no place value system. The digit or digits of lower value
is/are placed after or before the digit of higher value. The value of digits of lower

value is added to or subtracted from the value of digits of higher value. Certain
rules for formation of Roman-numeral is given below.

Rule 1 : The roman digits I, X and C can be repeated upto three times in succession to
form the numbers.
a. We know the value of I = 1, value of X is 10 and value of C is 100.
b. The value of I, X and C are added as :
I = 1 X = 10
II = 1+ 1 = 2 XX = 10 + 10 = 20
III = 1 + 1 + 1 = 3 XXX = 10 + 10 + 10 = 30
C = 100 CC = 100 + 100 = 200
CCC = 100 + 100 + 100 = 300
c. No digits is repeated in succession more than thrice, i.e., I, X and C cannot be repeated
more than 3 times.
d. The digits V, L and D are not repeated. The repetition of V, L and D is invalid in the
formation of numbers. (V = 5, L = 50, D = 500)
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Mathematics In Focus - 4