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# Final Friday Fix: August 2024 Challenge

30 August 2024

On the final Friday of each month, we set an Excel / Power Pivot / Power Query / Power BI problem for you to puzzle over for the weekend.  On the Monday, we publish a solution.  If you think there is an alternative answer, feel free to email us.  We’ll feel free to ignore you.

The Challenge

Suppose we are forecasting our company’s sales 10 years in advance.  We have specific sales estimates out to Year 5, but after that, we are simply provided with a growth rate.  We want a formula that will simply calculate the sales for any particular period.

However, there’s a twist.  For any period, we can apply a sales discount, which will discount the sales by a set value.  Additionally, it’s important to note that the first period will always just take the value in the Sales row less the sales discount.  Finally, in the scenario where we are given both a sales value and a growth rate, the growth rate will override the value whilst in the scenario where neither are given, sales growth is assumed to be zero [0].

We challenge you to find the most efficient formula to calculate the sales for a given period.  You can download the question file here.

As always, we have some requirements:

• the sales discount cannot make the net sales lower than zero [0], and is only applied to the period it is specified in, it does not accumulate
• you must do this with a single Excel formula, although it may be copied across for different periods
• no LAMBDA or LAMBDA helper functions (e.gLETBYROW or MAP) are allowed
• no Power Query or VBA allowed; this is a formula challenge.

Sounds easy?  Then give it a go.  There are various ways you could approach this, see if you can find the most efficient solution.  We’ll publish our solution in Monday’s blog.  In the meantime, have a great weekend.