Start with a pile of counters, then take some away. Count what's left — that's subtraction. Set how many you start with, then remove them one by one.
Subtraction can also mean the gap between two numbers. To do 52 − 47, don't take away — instead count up from 47 to 52. The hops you count are the answer: the difference is 5.
1. Missing number: 15 − ☐ = 9. What is ☐? 6 — because 15 − 9 = 6.
2. Word problem: Vi An had 30 stickers and gave away 12. How many are left? 30 − 12 = 18 stickers.
3. Inverse check: If 8 + 5 = 13, then 13 − 5 = ? 8 — subtraction undoes the adding.
4. Two steps: You have 20 sweets. You eat 5, then give away 7. How many left? 20 − 5 = 15, then 15 − 7 = 8.
Every adding fact hides a subtracting one. 8 + 5 = 13 also tells you 13 − 5 = 8 and 13 − 8 = 5. They're a team — that's why you can check a subtraction by adding back.
And remember: you can take away or count up the difference. Whichever feels easier, you get the same answer.