This paper is intended to be used in the classroom. It describes essentially every step of the construction of an Excel model to help solve Sudoku puzzles. For those up to moderate difficulty, it will usually solve the puzzle to completion. For the more difficult ones, it still provides a platform for decision support. The paper may be found useful for a lesson in which students, who, having some basic knowledge of Excel, are learning some of its lesser-known features, such as conditional formatting. It also generates a useful tool for working with Sudoku puzzles, from the very easiest right up to the ones often labelled as fiendish or diabolical. Fundamental mathematical concepts such as set intersection, set partition and reduction of set partition to singletons are very graphically illustrated by the present Excel model for Sudoku. Prominent spreadsheet concepts presented here are conditional formatting, names, COUNTIF, CONCATENATE. The paper is accompanied by a completed Excel model, constructed by using the steps described herein. No VBA code is employed; the whole thing is done with Excel formulas and conditional formatting.