**Square Roots**

Previously you learned how to square a number. For example, 7 ^{2} = 7 × 7 = 49 and 3 ^{2} = 3 × 3 = 9. The opposite of squaring a number is taking the square root of a number. The radical sign is used to indicate the square root of a number, so because 4 ^{2} = 16 and = 5 because 5 ^{2} = 25.

Numbers such as 1, 4, 9, 16, 25, 36, 49, etc., are called perfect squares because their square roots are rational numbers.

**Irrational Numbers**

The square roots of other numbers such as , , , etc., are called **irrational** numbers because their square roots are infinite, non-repeating decimals. For example and In other words, the decimal value of cannot be found exactly.

**Math Note:** The easiest way to find the square root of a number is to use a calculator. However, the square root of a perfect square can be found by guessing and then squaring the answer to see if it is correct. For example, to find , you could guess it is 12. Then square 12. 12 ^{2} = 144. This is too small. Try 13. 13 ^{2} = 169. This is still too small, so try 14. 14 ^{2} = 196. Hence, .

**Real Numbers**

The set of numbers which consists of the rational numbers and the irrational numbers is called the **real numbers.**

Practice problems for these concepts can be found at: Informal Geometry Practice Test.

### Ask a Question

Have questions about this article or topic? Ask### Related Questions

See More Questions### Popular Articles

- Kindergarten Sight Words List
- First Grade Sight Words List
- Child Development Theories
- 10 Fun Activities for Children with Autism
- Social Cognitive Theory
- Why is Play Important? Social and Emotional Development, Physical Development, Creative Development
- Signs Your Child Might Have Asperger's Syndrome
- A Teacher's Guide to Differentiating Instruction
- Theories of Learning
- Definitions of Social Studies