This is a free full-featured Office Suite that can run the Math on the Level 5-A-Day scheduling spreadsheets and is available for PC, MAC, Chromebook, and even a Raspberry Pi! If you don't have Microsoft Excel®, use LibreOffice.
OpenOffice™ for PC
This is another full-featured open-source Office suite that can run the Math on the Level 5-A-Day scheduling spreadsheets and is completely free! If you don't have Microsoft Excel®, download and use OpenOffice™ Calc.
This full-featured open-source Office suite for MAC is completely free! The Math on the Level 5-A-Day scheduling spreadsheets are fully compatible with OpenOffice™ Calc.
Microsoft Excel Online
If you are using the Math on the Level 5-A-Day Scheduling Spreadsheet but don't have Microsoft Office, another free option is to use Microsoft Excel Online. You must sign up for a Microsoft account in order to use it, and it is accessible only when connected to the Internet. However, it is free and works well.