Numbers, part of the iWork suite of office and productivity apps for iPhone and iPad, is Apple's attempt to make spreadsheets more mainstream. With Numbers you can easily and elegantly plan anything and everything from a checklist to budget, savings plan to schedule, team roster to party plan, invoice to cost projection, grade book to lesson chart, and much, much more. Apple includes a large assortment of templates to help get you started with most projects, but you can also make any custom layout you like.
Thanks to iCloud, you can also sync your Numbers documents between your iPhone and iPad, and with Numbers for Mac, as well as share and collaborate online via iWork on iCloud on iCloud.com. Leave comments on cells for others to view and much more.
If you collaborate with folks who use Microsoft Office, you can choose to save files in .xls and .xlsx formats so you can rest assured no one has any issues with compatibility. You also have the option to export files to PDF and other formats right within Numbers. Just like others can open your Numbers files in Excel, you can also open files made in Excel with Numbers.
For people that still gravitate towards Office products, it may be worth weighing your options between iWork and Office for iPad before deciding which office suite deserves your cash. Both are great options and contain powerful ways to create and manipulate spreadsheets. If you want the familiarity of Office, then check out Excel for iPad. If you prefer lots of template options and an easy to use interface and iCloud sync, Numbers is your best bet.
Numbers is $9.99 for older devices but should be available for free to any new iPhone, iPod touch, or iPad owner that purchased during or after the fall of 2013.