What This Drill Trains
Rounding is estimation in everyday clothes: shopping totals, travel times, and quick checks of whether an answer is reasonable. This rush asks you to round to the nearest ten so the “look at the ones digit” rule becomes automatic before you apply rounding inside larger calculations.
How to Think During the Round
Look only at the ones digit. If it is 0–4, round down to the lower ten. If it is 5–9, round up to the next ten. Mentally place the number on a number line between two tens and ask which neighbor is closer — with 5 always rounding up by convention in this curriculum.
You have 60 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.
Round 47
Thinking: Ones digit is 7 (≥ 5), so round up → 50.
Answer: 50
Round 32
Thinking: Ones digit is 2 (< 5), so round down → 30.
Answer: 30
Round 85
Thinking: Ones digit is 5 → round up → 90.
Answer: 90
Common Mistakes
- Rounding to the nearest hundred by accident when the problem asks for tens.
- Treating 5 as “round down” (this site uses the standard round-half-up rule).
- Changing the tens digit incorrectly when rounding up across a multiple of 100 (e.g., 95 → 100).
Practice Tips
- Say “down” or “up” out loud once before typing for the first few rounds.
- Practice the borderline cases (x5 and x4) until they feel boring.
- Later you will use this same decision inside round-and-adjust multiplication.
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.