Macro to calculate Expected Sales

I have an excel sheet where I have data for everyday sales. Please find the dummy sheet below.


Date Total Sales Expected sales
1st Nov 2000 2000
2nd Nov 2100
3rd Nov 2110

Here I have a formula for expected sales which is Total sales till now + (Total Expected sales for previous day/remaining number of woking days). Hence expected sales for 2nd nov is 2000+2000/20 = 2100, for 3rd nov its 2000+2100/19 = 2110(excluding decimals). Likewise I need to calculate the expected sales for the remaining number of working days of the month. I want to automate the formula with the help of a macro.
Please assist.