Math 7 · Unit 3, Lesson 1: Adding Signed Numbers · Tile 1 of 5
Money You Have, Money You Owe
Signed numbers, opposites, and net worth
A signed number has a sign that tells which side of 0 it is on. Positive numbers are greater than 0. Negative numbers are less than 0. Zero is neither.
The words
| Elle (math-speak) | Finn (plain English) |
|---|---|
| Signed number | A number with a + or − sign. +5 is $5 you have. −5 is $5 you owe. |
| Rational number | Any number you can write as a fraction of integers. Whole numbers, fractions, decimals, and their opposites. |
| Opposite (additive inverse) | Same amount, other side. Having $4 and owing $4 are opposites. |
| Absolute value | How many dollars, without saying have or owe. |−6| = 6. |
| Sum | Your net worth: everything you have, minus everything you owe. |
Opposites
The opposite of a number is the same distance from zero, on the other side of zero. The opposite of 4 is negative 4.
If 4 means you have 4 dollars, then negative 4 means you owe 4 dollars. Same amount, other side.
Opposites cancel
| Have (+) | Owe (−) |
|---|---|
| $5 | |
| $5 | |
| Net worth Pay off the $5. Net worth: $0. | |
The sum of a number and its opposite is zero.
If you have 5 dollars and you owe 5 dollars, pay it off. Your net worth is zero. You're even.
Absolute value
Absolute value is a number’s distance from zero. Absolute value is never negative.
Absolute value is how many dollars, without saying whether you have them or owe them. Having 6 dollars and owing 6 dollars are both 6 dollars.
NC standard: NC.7.NS.1.