# 8th Grade Math : Number Sense

## Example Questions

### Example Question #1 : Number Sense

Which of the following answer choices displays a rational number?

Explanation:

Our answer choices consist of two types of numbers: rational numbers and irrational numbers. In order to correctly answer this question, we need to know the difference between the two types of numbers.

Rational numbers are numbers that we use most often, and can be written as a simple fraction.

Irrational numbers cannot be written as fractions, and are numbers that have decimal places that never repeat or end.

In this case,  is our only rational number because it can be written as a simple fraction:

### Example Question #2 : Number Sense

Solve:

Explanation:

In order to solve this problem, we need to recall our exponent rules:

When our base numbers are equal to each other, like in this problem, we can add our exponents together using the following formula:

Let's apply this rule to our problem

Solve for the exponents

We cannot leave this problem in this format because we cannot have a negative exponent. Instead, we can move the base and the exponent to the denominator of a fraction:

Solve the problem