Well, you may apply formattings (e.g numbers formatting) to your desired sheet cells using Aspose.Cells APIs. See the document on how to apply different display formats to a cell, a row, a column, etc.
Especially for your tasks, you may try referring to the sub-topic “Using Custom Number Formats” with example. We recommend you to kindly open a new Workbook into MS Excel manually and add some data to the cells, now apply your desired (custom) formatting in a cell. Now use same custom string when performing the task via Aspose.Cells APIs in code.
If you still find any issue, kindly do attach your expected file with your desired formatting (you may create the file into MS Excel manually) and attach it, we will check and help you on how to do it via Aspose.Cells APIs.
PS. please zip the file prior attaching.