Basic Algebra/Introduction to Basic Algebra Ideas/Simple Operations

Vocabulary

Operation

Equals Sign

Adding

Subtracting

Multiplying

Dividing

Remainder

Parity

Common denominator

Absolute value

Inverse

Lesson

An ''operation" is a thing you do to numbers. You use signs like: +, –, ×, or ÷ for operations.

The Equals Sign is not an operation. You use the " = " sign for the Equals Sign. It is a special sign that you put between two things that are the same.

Adding

Adding is a way to put two numbers together. You use the " + " sign for the adding operation. If you have 5 apples and a friend has 6 apples, you and your friend have 11 apples. This is 5 + 6 = 11 using the signs of Math, and is read "five plus six equals eleven".

Order is not important when adding. 2 + 3 is the same as 3 + 2.

Subtracting

Subtracting is a way of taking a number out from another number. It is the opposite of adding. You use the " – " sign for the subtracting operation. If you have 36 apples and give 11 to a friend, you then have 25 apples. This is 36–11 = 25 using the signs of Math. Read this "thirty-six minus eleven equals twenty-five".

Order is important when subtracting. 3 – 2 is not the same as 2 – 3.

Multiplying

Multiplying is a way of adding a number many times. You use the " × ", " • " or " * " sign for the multiplying operation. If you have 4 apple trees and every tree has 25 apples, you have 100 apples. This is 4 × 25 = 100 or 25 + 25 + 25 + 25 = 100 in the signs of Math. The first way is shorter and easier to use.

Multiplying 25 by 4 is the same as adding 25, 4 times or adding 4, 25 times.

4 x 25 = 100 should be read "four times twenty-five equals one hundred".

Order is not important when multiplying. 2 × 3 is the same as 3 × 2.

Dividing

Dividing is a way of subtracting a number many times. It is the opposite of multiplying. You use the " ÷ " or " / " sign for the dividing operation. If 3 friends take an equal part of a bag of 12 apples, every friend gets 4 apples. Or, you may take away (subtract) 3 apples from the bag of 12 apples, exactly 4 times until the bag is empty. This is 12 ÷ 3 = 4 or 12 – 3 – 3 – 3 – 3 = 0 in the signs of Math.

12 ÷ 3 = 4 should be read "twelve divided by three equals 4".

Order is important when dividing. 3 ÷ 2 is not the same as 2 ÷ 3.

Example Problems

• 3 + 4 = 7
• 5 – 3 = 2
• 6 × 2 = 12
• 13 + 14 = 27
• 36 – ５ = 31
• 21 – 9 = 12
• 8 × 3 = 24

Practice Games

• Addition Game
• Subtraction Game
• Multiplication Game

Practice Problems

1. 6 + 8 =
2. 3 + 4 =
3. 10 + 15 =
4. 28 + 13 =
5. 36 – 11 =
6. 16 – 3 =
7. 7 × 5 =
8. 8 × 4 =
9. 6 × 6 =
10. 14 ÷ 7 =
11. 15 ÷ 3 =
12. 40 ÷ 5 =