What it is about
You see a grid of 5 by 5 squares. Some squares contain the letters A, B, C, D or E. One square has a question mark. You have to find the letter for this square and choose it from A to E.
20 tasks, 25 minutes, so about 75 seconds per task. Source: testas.de: structure of the digital TestAS.
The rule
Each letter appears exactly once in every row and exactly once in every column. There are no more rules. In easy tasks, the question mark follows directly. In hard ones, you first have to fill other squares in your head.
An example from our Trainer
Our own generator created this example. A dot stands for an empty square.
| Col. 1 | Col. 2 | Col. 3 | Col. 4 | Col. 5 | |
|---|---|---|---|---|---|
| Row 1 | D | · | · | · | C |
| Row 2 | · | A | E | B | · |
| Row 3 | · | · | D | · | E |
| Row 4 | · | E | ? | D | · |
| Row 5 | E | · | · | · | A |
Which letter belongs at the question mark?
Show solution
C. Here you first have to fill another square.
- Row 2, column 1: Row 2 already contains A, B and E. Column 1 contains D and E. Only C remains.
- Now row 4: It still needs a C. Column 1 now has a C, and column 5 has a C in row 1. For C, only column 3 is left in row 4, so the question mark.
How to proceed
- Count first. In which row or column of the question mark are the fewest letters missing?
- Rule out. In your head, strike out all letters that already stand in the row or column of the question mark.
- If more than one remains, ask the other way round: where in this row can a certain letter still go at all? Often there is only one square.
- Keep intermediate steps short. Fill only the squares you need for the question mark, not the whole grid.
Common mistakes
- Checking only the row and forgetting the column.
- Losing an intermediate step in your head and starting again. A fixed order helps: first the row, then the column.
Open
The preparation PDF (as of April 2022) names 16 tasks in 20 minutes, the website 20 tasks in 25 minutes. We follow the website. See Structure.