Num Sum is a free online, sharable social spreadsheets. You can copy and paste data from Excel into your Num Sum spreadsheet. You can also work on Num Sum spreadsheet offline and save your Num Sum spreadsheet to your local disk while the internet connection is down.

With Num Sum, you can:

1. Track your records, lists and data online
2. Share with everybody or with just your close contacts
3. Connect with others who have similar interests

It is easy to use, simply log in to Num Sum, create a spreadsheet, tag it, and share the URL with friends or anyone on the web or post it to your blog or website with a snippet of HTML code.

The Num Sum formula language supports functions and mathematical operators. You can signup to try Num Sum.