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Basic Subtraction

The Hook

If you have 5 apples...

What is it?

Taking a smaller number away from a larger one to find the difference.

Time Travel (History)

Ancient merchants used subtraction tokens to calculate profit and loss.

Cheat Code

Think: 'How far apart are these two numbers on the number line?'

Practice This Now!

The Field Guide

In Plain English: Subtraction is finding the distance. If you are on Step 10 and you want to go back to Step 2, subtraction tells you how many steps to walk.

In The Real World: Battery Life. You have 80% and use 15%. How much is left?

How To Do It

  1. Write the big number on top.
  2. Write the small number on bottom (line up the right side!).
  3. Start at the ones column (far right).
  4. Top minus Bottom equals Answer.
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Booby Trap!

Swapping the order! 10 - 2 is easy. 2 - 10 is a totally different beast (negative numbers).

Real World Challenge
"A gamer has 100 HP. They take 15 damage from a slime. How much health is left?"
The Logic: 100 - 15 = 85 HP.

Training Drills

Vertical
9 - 4 --- 5
Standard setup.