Help setting up a a spread sheet to help my semi retired Dad

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I need help! My Dads hobby is costing him money I would really appreciate some advice on a spreadsheet I’m working on

So my Dad grows plants and makes garden furniture and sells them which is great however, he has actually been selling stuff at a massive loss. So I have created a sheet where:

cell 1 cost price
cell 2 vat %
cell 3 vat cost
cell 4 mark up ((c1+c3)+a percentage of the result of c1+c3)
cell 5 retail price (c1+c3+c4)

I am trying to make it so the mark up can be a selection drop down of a percentage of 5% increments so when he sells something a friend he can select for eg: 0% to a neighbour say 15% and if he does a market eg 100% but I am not very good at excelling

Can anyone point me in the right direction?

Many thanks

1 Reply
check out the Data tab, Validation option. But I think you might also help your dad by letting him do some simple math by asking him questions such as how much does it really cost to build that piece of furniture (materials -all of them-, time, energy, heating, ...). If he does the math himself I expect he'll get more insights.