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Adding Two Negatives

Part of the Numbers & Operations section of Coddy's Pre-Algebra journey. Lesson 15 of 57.

What is $-5 + \left(-3\right)$ ? Start at -5 on the number line. Adding a negative number walks you to the left, so three more steps left lands on -8. The sizes combine, 5 and 3 make 8, and the answer keeps the minus sign.

$Number line from -10 to 2 with -8, -5 and 0 marked$

From -5, three steps left lands on -8.

Why does the sum stay negative? Think of money owed. Owing 5 dollars and then owing 3 more means you owe 8. Nothing positive arrived to pull you back toward zero, so you only moved further below it.

Adding a negative is the same as taking away its size: $-5 + \left(-3\right)$ and $-5-3$ both land on -8. Books and calculators often write it the short way, $-5-3$ , so read that as two negative numbers being combined.

Challenge

Work out $-9 + \left(-14\right)$ . Type the result.

Try it yourself

-9-14

Simplify

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Numbers & Operations

1Order of Operations

Your First Answer Left to Right Parentheses First Brackets Inside Brackets The Fraction Bar Groups Recap: Order of Operations

4Adding Integers

Adding Two NegativesDifferent Signs Zero Pairs Adding Several Integers Recap: Adding Integers

7Exponents

Repeated Multiplication Squares and Cubes Powers of Ten Negative Bases Where the Minus Sits Recap: Exponents

10Numbers in Stories

Temperature Changes Money Owed Up and Down Equal Shares Recap: Number Stories

2Mental Math

Friendly Pairs Take Away the Total Recap: Mental Math

5Subtracting Integers

Add the Opposite Subtracting a Negative Plus and Minus in a Row Distance Between Numbers Recap: Subtracting Integers

8Square Roots

Perfect Squares Undoing a Square Roots in Expressions The Root Sign Groups Between Two Whole Numbers Recap: Square Roots

11Final Challenges

Final: Every Rule at Once Final: Roots and Powers Final: The Freezer Final: Over the Bar Final: On the Line

3Negative Numbers

Below Zero Opposites Greater or Less Absolute Value Recap: The Number Line

6Multiplying and Dividing

Negative Times Positive Two Negatives Counting the Negatives Dividing Integers Zero in Division Recap: Multiply and Divide

9Putting It All Together

Powers Before Products Negatives Inside Negative Bases in Sums Everything at Once Recap: The Full Order