Painting a test on a hundred squares
A notice board lists 1 to 100, ten in each row. The rows make a grid. Each number has its own box, called a cell. A multiple of 11 is 11, 22, 33 and so on.
Loading lab…
Step 1 of 4
- Numbers 1 to 100, ten to a row.
- One step right adds 1. One step down adds 10.
- Shade every multiple of 11: 11, 22, 33, up to 99.
- Each shaded cell sits one row down and one column right of the last.
The rule
One step right adds 1. One step down adds 10. So one step down and one step right adds 10 + 1 = 11. The multiples of 11 line up going down and right. Each is one cell down and one right of the one before.
One step down and left adds 10 − 1 = 9. So the multiples of 9 go the other way, down and left.
Rule: One step right adds 1. One step down adds 10.
| Multiples of | Cells shaded | Where they fall |
|---|---|---|
| 11 | 9 | each one down and one right |
| 9 | 11 | 9 to 81 go one down, one left. Then 90 and 99 |
| 5 | 20 | the 5th and 10th columns |
| 2 | 50 | the 2nd, 4th, 6th, 8th, 10th columns |