In Excel: Finding the third variable when you know any two of the three.

Question

How do I create a formula that allows me to know any two of three variable to find the third.  For example, if I know the cost of an item and the tax rate, it will give me the total. However if I know the total and tax rate it will give me the item cost.

Is it possible without using circular references? 

Thanks, Ken

Answer 1

Hi,

See the snip below. In each case it's the yellow cells that we don't know. The formula in each of the yellow cells is shown in Col D in the snip.

Answer 2

Hi,

if you know the total Value

and you search for the value before tax

try this

if tax is say, 23%

then

item cost = round( [total Value]/1.23, 2)

Answer 3

Hi Mike,

Let me give a better example of what I am trying to do.

Cost     %Increase      Total

Is there a way of entering any two variables to get the third without it becoming a circular reference? 

Ex. If I punch in the cost and increase, it will give me the total.  However, if I know the cost and total, it will give me the %Increase. I have got it to work by putting formulas in each cell and overwriting the formulas with numeric values but I get circular references and it glitches sometimes.

Ken