Positive and Negative Numbers
Understand positive and negative numbers as describing quantities with opposite directions or values; use them in context such as temperature, floors in a building, and bank balances
What a learner can do afterwards
- Represent positive and negative numbers on a number line and explain what zero means in context
- Add a positive or negative number to any integer using number line reasoning
- Subtract a positive or negative number from any integer, understanding that subtracting a negative is equivalent to adding
1 · Read
You already know how to read a thermometer, so you have a head start here. Numbers can go two directions from zero. Positive numbers sit above zero, like +5. Negative numbers sit below zero, like -3. Zero itself is the starting point that everything else is measured from. Walk up the line to add and down it to take away. Taking away a negative turns you back up: 5 - (-10) is the same as 5 + 10.
A parking garage floor is labeled -2. The lobby is floor 0. The offices are on floor 3. Traveling from the parking garage to the offices means going up 5 floors: -2, -1, 0, 1, 2, 3.
Subtracting a negative number acts like adding. If you take away a $10 debt, you end up $10 richer. That is why 5 - (-10) gives the same answer as 5 + 10.
Positive numbers sit above zero, negative numbers sit below zero, and subtracting a negative number is the same as adding a positive one.
2 · Watch
3 · Play
Step down past zero and see how far below you have gone.
Take it off screen
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
14 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.