calculator creation, find missing value
 

I would like to build a calculator using Excel but am unsure of some of the
formulations.

I would like to create a calculator that will return any missing fourth
value when three values are given.

The formula is similar to y = a * b* c

Depending on the real world circumstances, any of three values are present
but the fourth is missing. Is there a formula, expression, function, or
series of if statements that will do this?

Is there a way for the user to type in the values but not destroy the
underlying formulas/functions keeping the caculator working? This might be a
good opportunity for me to learn VBA if this is required. Suggestions would
be helpful.

Thank you,
philr

calculator creation, find missing value
 

Put labels in column A, and use column B for entry - let's say B2:B5 with y in B2, etc.

Then in C2 to C5, use the formulas

=IF(B2<"",B2,IF(COUNTA($B$2:$B$5)=3,B3*B4*B5,"Ent ries not valid"))
=IF(B3<"",B3,IF(COUNTA($B$2:$B$5)=3,B2/B5/B6,"Entries not valid"))
=IF(B4<"",B4,IF(COUNTA($B$2:$B$5)=3,B2/B3/B5,"Entries not valid"))
=IF(B5<"",B5,IF(COUNTA($B$2:$B$5)=3,B2/B3/B4,"Entries not valid"))

HTH,
Bernie
MS Excel MVP


"philr" wrote in message
...
I would like to build a calculator using Excel but am unsure of some of the
formulations.

I would like to create a calculator that will return any missing fourth
value when three values are given.

The formula is similar to y = a * b* c

Depending on the real world circumstances, any of three values are present
but the fourth is missing. Is there a formula, expression, function, or
series of if statements that will do this?

Is there a way for the user to type in the values but not destroy the
underlying formulas/functions keeping the caculator working? This might be a
good opportunity for me to learn VBA if this is required. Suggestions would
be helpful.

Thank you,
philr