91Ó°ÊÓ

• The set $\left\{1,2,3,4,5,...\right\}$ is called the set of natural number.
• The set $\left\{0,1,2,3,4,5,...\right\}$ is called the set of whole number.
• The set $\left\{-3,-2,-1,0,1,2,3,...\right\}$is called the set of integer number.
• The set of rational number has numbers in the ratio form $\frac{m}{n}$, where $m$ and n are integers and n is non-zero. The decimal form of a rational number is either a terminating or repeating decimal.
• A real number that is not rational is irrational. The decimal form of an irrational number is neither terminating nor rational.
• Combine sets of rational and irrational number is real number.

Following vein diagram shows relationship between different sets

Where, the symbols denote

Where, the symbols denote

N- Natural number

W- Whole number

Z- Integers

Q- Rational number

I- Irrational number

R- Real numbers

As, 121 is a whole number and square root of this number is 11 which is also a whole number.

Also 11 is a natural number

So, using above vein diagram, $\sqrt{121}$ is a natural number, a whole number, an integer, a rational number and a real number.

Thus, $\sqrt{121}$ belongs to the sets of natural number, whole number, integer, rational number and real number.