Subtraction Within 20
20 questions · 60 seconds · subtraction within 20
Free · no login · instant feedback on every answer
Get fast at subtraction within 20 — the partner skill to addition facts and the second pillar of early fact fluency. The game asks 20 subtraction questions with numbers up to 20, always with whole-number answers, and shows instantly whether each answer is right.
Subtraction fluency lags addition for most students because it gets less practice, not because it is harder. A focused 60-second drill each day — especially one that corrects mistakes immediately — closes that gap quickly.
Tips That Make It Stick
- Think addition. For 15 − 8, ask "8 plus what makes 15?" Fact families mean every addition fact a student knows is a subtraction fact too.
- Subtract through ten. For 13 − 5: take 3 to reach 10, then 2 more to reach 8. Breaking at ten mirrors the make-ten addition strategy.
- Count back only for small gaps. Counting back works for 12 − 3 but falls apart for 17 − 9 — that is when think-addition should take over.
Frequently Asked Questions
What does subtraction within 20 mean?
Subtraction problems where every number involved is 20 or less, like 16 − 9 or 12 − 5. It is the standard 1st and 2nd grade fluency goal that prepares students for multi-digit subtraction with regrouping.
Why is subtraction harder than addition for kids?
Mostly practice imbalance — children encounter addition earlier and more often. Teaching fact families ("8 + 7 = 15, so 15 − 7 = 8") lets subtraction ride on addition fluency instead of being memorized separately.
Can I turn off the timer?
Yes — after loading the practice game, open game settings and switch off the time limit for untimed practice. All other preset options can be adjusted there too.
📝 Matching Printable Worksheets
Prefer paper practice? These free PDF worksheets cover the same skill — each includes an answer key: