Application of exponents in real world
One of the application is to measure the strength of earthquakes on the Richter scale. A level 1 earthquake is 1 × 10^{1}, a level 2 earthquake is 1 × 10^{2}, and a level 7 earthquake is 1 × 10^{7}, etc.
A numerical expression is a mathematical phrase that contains only numbers and mathematical operations. For example, “6 ÷ 3 – 2 + 1” is a numerical expression. In an expression involving multiplication, the quantities multiplied are called factors. For example, in an expression: “3 × 7 × 11 × 13”, 3, 7, 11 and 13 are called **factors** of an expression.

Exponents are used to represent repeated factors in multiplication. For example, the expression 6^{4} represents the number that we obtain when 6 is used as a factor 4 times. The number 6 is called the **base** (sometimes as radix), the number 4 is called the **exponent** (or **index**) and the expression 6^{4} is called a **power**. The exponent in a power represents the number of times the base is used as a factor.