Repeat a formula after every nth column

Hello All,

I am trying to create a formula by which I can calculate sales of a product after every n months.

For example

Inputs:
Number of Units = 10
Price per unit = 50
Frequency of sale = every 6 months
First sale in 2nd month.

Output:
Month 2 = 500
Month 8 = 500

Example is attached for refrence.

Thank you for the help.

Thank you for posting the solution. All three formulas work except if the Frequency < First sale month.

For example if the Frequency is every 2 months and first sale is month 5, the first calculation does not show in the correct month.

Thanks for the help.

Added a clause to check if it's after the first sale month.

Thank you alexdi, Calc3 works perfectly. Thanks for the quick response.