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## What's in the Middle?

The goal of a $3\times 3$ Calcdoku puzzle is to fill the squares with a single digit each, with the following rules:

1. Each of the digits $1$ through $3$ is used exactly once in each row and column. (There is no region rule as in Sudoku.)

2. Any marked region indicates a number and an operation $(+,-,\times,$ or $\div).$ The operation applies to digits in the region and, when applied to the digits in some order, they result in the given number. In the example below, the region marked $“\, 7+"$ must be filled with three digits selected from $1$ through $3$ that have a sum of $7.$ Digits can be repeated in a marked region, but not in a row or column.

Keep reading to see two example puzzles, or jump straight to the daily challenge below.