You may have done a Calcdoku puzzle before, but have you ever done one with *complex numbers*? That is, instead of just integers, we also have numbers like $1+i$ or $-3i.$ More generally, that's numbers of the form $a+bi,$ where $a$ and $b$ are real numbers and $i$ is the imaginary unit, defined by $i^2=-1.$

The Calcdoku rules remain the same:

- Each square needs to be filled with one of the given numbers, and each number given is used exactly once in each row and column. (There is no region rule as in Sudoku.)
- Any marked region indicates a value and an operation $+,-,\times,$ or $\div.$ The operation applies to numbers in the region, and when applied to the numbers in some order, they result in the given value. Numbers can be repeated in a marked region, but not in a row or column.

Keep reading to see two example puzzles — one traditional, and one with complex numbers — or jump straight to the daily challenge below.