# Back working formulas

#### chucky48316

##### New Member
Don't know how to even word this so I couldn't search for an answer but any help would be appreciated....

What I'm looking to do is get cells to work together, sort of like a 2 way trigger.. i.e.

setting up a loan payment....

one cell is rate, one cell is duration, and the other cell is value of loan, than you have a solution cell=pmt(rate, nper, pv).

I want it so if you put in any 3 of the 4 values it will solve for the last one.

Again thanks for any help even if just pointing me to a already answered post.

### Excel Facts

VLOOKUP to Left?
Use =VLOOKUP(A2,CHOOSE({1,2},\$Z\$1:\$Z\$99,\$Y\$1:\$Y\$99),2,False) to lookup Y values to left of Z values.

#### Domenic

##### MrExcel MVP
Assumptions:

B2 contains the payment amount

B3 contains the interest rate

B4 contains the number of periods

B5 contains the loan amount

Formula:

=IF(COUNT(B2:B5)=3,CHOOSE(MATCH(TRUE,B2:B5="",0),PMT_Formula, RATE_Formula,NPER_Formula,PV_Formula),"")

...confirmed with CONTROL+SHIFT+ENTER. Replace PMT_Formula, RATE_Formula, etc., with their respective formulas.

Hope this helps!

#### Dufus

##### Board Regular
chucky48316,

You could also look at Goal Seek as another option.

Dufus

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