What This Drill Trains
Two-digit subtraction is where many learners freeze because of borrowing. Mental strategies — subtracting tens then ones, or adding up to the larger number — remove that panic. This drill builds confidence with everyday differences: discounts, remaining time, and comparing quantities.
How to Think During the Round
Try adding up when subtraction feels sticky: for 83 − 57, count from 57 to 83 (57 → 60 is 3, 60 → 83 is 23, total 26). Or decompose: 83 − 50 = 33, then 33 − 7 = 26. Compensation also helps: 83 − 60 = 23, then add back 3 because you subtracted 3 too many → 26.
You have 90 seconds. Accuracy still outranks raw speed: one calm method repeated well beats a streak of guesses. After the timer ends, notice which problems felt sticky — that short review is where real improvement happens.
Worked Examples
Study these before you press Start. Try to recreate the thinking without looking at the answer first.
72 − 38
Thinking: 72 − 40 = 32; add back 2 → 34. Or 72 − 30 = 42; 42 − 8 = 34.
Answer: 34
90 − 46
Thinking: 90 − 50 = 40; add back 4 → 44. Or 90 − 40 = 50; 50 − 6 = 44.
Answer: 44
65 − 29
Thinking: 65 − 30 = 35; add 1 → 36.
Answer: 36
Common Mistakes
- Borrowing incorrectly and reducing the tens digit twice.
- Subtracting the smaller ones digit from the larger regardless of place (classic digit reversal).
- Forgetting to add back when using “subtract a friendlier number” compensation.
Practice Tips
- Prefer compensation whenever the subtrahend ends in 8 or 9.
- Check by adding your answer to the subtrahend — it should rebuild the start number.
- Practice a few problems that cross a ten boundary before starting the timer.
Suggested Session Plan
- Read the method section once if this skill is new.
- Cover the answers and re-solve the three worked examples aloud.
- Start the timed round and stick to one strategy.
- Replay once, then write down any fact or pattern you missed.
- If the same error repeats, open the full lesson for more examples and a practice set with an answer key.
Full explanation, extra worked examples, and practice problems for this skill: open the related stage lesson .
Prefer a structured curriculum instead of random drills? Browse all learning stages or read the complete mental arithmetic guide . More timed drills live on the games hub.