# How to perform certain calculations in Google Sheets?

Just trying to create a simple sheet to track my weight loss. Here is a link to my sheet so far so you can see what I'm talking about. Weight Loss Sheet

So far I have gotten the C column working properly. Now I just need help with D and E.

1: In D (I have added examples) I would like it to calculate the difference between the current and previous weight entry with a formula that can auto-fill (keeping in mind that entries are often separated by sporadic empty cells). So each number in C minus the entry above it.

2: Next in E would like it to show the average every 7 days that will change depending on my rate of loss from D. Added a few manually calculated numbers as an example. Pretty sure I have calculated it wrong though. Arg! Should have stayed in school :)

This is my very first time using sheets so I am an absolute beginner. Never even used Excel. I have tried googling for a solution but I couldn't find anything. I think the problem is I don't know exactly what to search for.