Negative Decimals

Part of the Decimals, Percents & Ratios section of Coddy's Pre-Algebra journey. Lesson 5 of 53.

At night it is $-3.5$ degrees. By morning it is 1.25 degrees warmer. It is still below zero: $-3.5+1.25$ is -2.25.

$From -3.5, a move of 1.25 to the right lands on -2.25, still left of 0$

The size of a number is its distance from zero. Here the signs are different. So subtract the sizes: 3.50 minus 1.25 is 2.25. Then use the sign of the number with the bigger size. Here that is minus.

Challenge

A diver is at $-6.4$ metres, below the surface. She swims up 2.75 metres: $-6.4+2.75$ . Where is she now?

Try it yourself

-6.4+2.75

Simplify

All lessons in Decimals, Percents & Ratios

1Decimals

Place Value Rounding Decimals Recap: Decimals

4Dividing Decimals

Dividing by a Decimal Dividing by 10 and 100 Dividing by a Whole Number Unit Price Recap: Dividing

7Percent Problems

Finding the Whole Discounts Tax and Tips Percent Increase Percent Decrease Recap: Percent Problems

10Proportions

Solving a Proportion Cross Products Scale Drawings Percent as a Proportion Recap: Proportions

2Adding and Subtracting

Line Up the PointsNegative DecimalsMaking Change Recap: Add and Subtract

5Fractions and Decimals

Fraction to Decimal Decimal to Fraction Repeating Decimals Ordering Both Kinds Recap: Fractions and Decimals

8Ratios

What a Ratio Is Simplifying Ratios Equivalent Ratios Sharing in a Ratio Recap: Ratios

11Final Challenges

Final: Decimals and Percents Final: The Jacket Final: Out of a Hundred Final: The Apple Stall Final: On the Line

3Multiplying Decimals

Multiplying Decimals Times 10, 100, 1000 Bigger Products Buying by Weight Recap: Multiplying

6Percent Basics

What Percent Means Percent of a Number Percent as a Decimal What Percent Is It Recap: Percent Basics

9Rates

Unit Rates The Better Buy Speed, Distance, Time Converting Units Recap: Rates