Help with a DATE formula

[Max_ie]

Hi, newbie here... I am wanting to have my spreadsheet keep track of my Crypto auto-buys.

So, each week my cryptocurrency site automatically buys a certain amount Bitcoin (BTC) and it is added to my portfolio (dollar-cost-averaging) via a recurring buy order.

Now I want that reflected in my Crypto spreadsheet. So that every 7 days the spreadsheet updates the cells with a new total dollar amount invested for each coin.

So for example, assuming that cell C3 shows my current amount invested in BTC as $5000, then something that would reflect that (if todays date = (previous date + 7 days) then (c3=c3+$50)). Therefore showing a new total of $5050 in C3 for BTC total invested.

Is something like this possible?

Cheers

Muddypaw

[#2]

@Max_ie 

Here is an example with your details.

Example in the attached file.

Wish you a merry xmas

[#3]

@Max_ie You could use a formula that calculates the number of whole weeks that have past since your first buy. In its simplest form, that could look something like this:

where A5 contains =TODAY()