How To Define Custom Number Format in Excel
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Right click on the marked area (1), and choose format cells (2).
Click custom and set the customized number under type.
Examples:
To display 123456.78 as 123456.8 use ####.#
.123 as 0.1 use 0.#
5.25 as 5 1/4 use # ???/???
Note: You can even format colors. Just write [color]
Template
You can download the Template here – Download
Further reading: Basic concepts Getting started with Excel Cell References