# Range of Observations

Posted in Terms Defined

The difference between the highest and lowest observation is called the range of the observations.

For example, consider the following observations:

2, 10, 5, 34, 98, 54

The highest observation is 98 and the lowest observation is 2.

So, the range of the observation is

= 98 - 2

= 96

# Important Statements

Posted in Terms Defined

• A factor of a number is an exact divisor of that number.
• A number for which sum of all its factors is equal to twice the number is called a perfect number.
• The numbers other than 1 whose only factors are 1 and the number itself are called Prime numbers.
• Numbers having more than two factors are called Composite numbers.

# Fraction

Posted in Terms Defined

A fraction means a part of a group or of a region.

for example $$\frac{2}{3}$$ is a fraction

where 2 is numerator and 3 is denominator.

Proper Fraction - In a proper fraction the numerator is always less than the denominator. For example $$\frac{4}{7}$$, $$\frac{21}{43}$$

Improper Fraction - In a improper fraction the denominator is always less than the numerator. For example $$\frac{7}{4}$$, $$\frac{43}{21}$$

Mixed Fractions - A mixed fraction has a combination of a whole and a part. For example $$3 \frac{1}{2}$$, $$7 \frac{4}{7}$$

# Rational Numbers

Posted in Terms Defined

A number which can be written in the form $$\frac{p}{q}$$, where p and q are integers and q ≠ 0 is called a rational number.

For e.g.

$$\frac{-2}{5}$$, $$\frac{6}{7}$$

# Roman Numerals

Posted in Terms Defined

The symbols used in Roman numerals are:

I ---> 1; V ---> 5; X ---> 10; L ---> 50; C ---> 100; D ---> 500; M ---> 1000

Rules for the system are :

a) If a symbol is repeated, its value is added as many times as it occurs:

i.e. II is equal to 2, XXX is equal to 30, CC is equal to 200

b) A symbol is not repeated more than three time. But the symbols V, L and D are never repeated.

c) If a symbol of smaller value is written to the left of a symbol of greater value, its value get added to the value of the greater symbol.

i.e. VI is equal to 5 + 1 = 6; CXX is equal to 100 + 10 + 10 = 120

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.

i.e. IV is equal to 5 - 1 = 4; XC is equal to 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.