100-cell grid: timed addition, subtraction and multiplication
For parents and teachers of children in Years 1 to 4. Your child fills a 10×10 grid (or a smaller one) on this screen, and every answer is marked the moment it is typed. Free, no sign-up, and it prints with an answer key.
How to use it with your child
- Pick +, − or × and a grid size. Start small (3×3 or 5×5) for younger children.
- Tap Start on this device and hand over the screen. The clock starts with the first number your child types.
- Your child fills each square left to right, row by row: the number on the left combined with the number on top. A red ○ appears on each right answer; a wrong one shows the right number in small red.
- At the end, tap Fix the ones you missed. Fixing mistakes is the part worth praising.
- Do the same grid a few days running and watch the time come down. The personal best stays on this device.
- To print, choose A4, B5 (JIS) or Letter and tap Print sheet. The answer key prints on its own page, and the QR code on the sheet opens the answers on your phone.
Which school years it suits
Addition and subtraction grids suit Years 1–2 (P1–P2, 小1–2, 초1–2) once children know their number bonds to 20. Multiplication grids suit Years 2–4, after the times tables have been learnt. Many families use one grid a day for a few minutes.
Why a 100-cell grid works
The 100-cell grid (百ます計算, hyakumasu keisan) is a daily routine in many Japanese classrooms. The same short task, done every day against the clock, turns slow counting into quick recall, and the child can see their own progress in seconds.
Subtraction grids use 10 to 19 down the left and 0 to 9 across the top, the classic layout, so every answer needs a quick take-away across ten.
Ready-made links
- 10×10 addition grid
- 10×10 subtraction grid (10–19 take away 0–9)
- 10×10 multiplication grid
- 5×5 addition grid for beginners
- 3×3 addition grid for preschoolers
Questions parents ask
How long should a 100-cell grid take?
It varies a lot. Many children start at three to five minutes for a 10×10 addition grid and get faster with daily practice. Compare your child with their own personal best, not with other children.
Can I print the same grid for a whole class?
Yes. The sheet number in the link (for example `seed=4821`) always makes the same grid. Print it once per pupil, or change the number for a different grid with its own answer key.
Why does the next square come up before my child presses OK?
Once enough digits are typed, the grid moves on by itself to keep the pace up. Add `auto=0` to the link if you would rather your child presses ↵ each time.
Is anything sent to Pencilhop?
No. Times and personal bests stay on this device. Only an anonymous count that a grid was finished may be sent.