# PW discount factors - monthly

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#### KenRossman

##### Senior Member
Can anyone point me to an excel template or an online source for monthly compound interest tables (looking for 15% to 18% - 24 months)

Or help with HP12C keystrokes - Can figure out annual but going nuts trying to figure out monthly

tia - ken

#### Howard Klahr

##### Senior Member
here is the formula for the present value factor 1/(1+i/12)^n
replace i with the interest rate and n with the desired period

for present value of an annuitiy (i.e. \$1 per period) the the excel formula is
=pv(rate/12,nper,pmt) replace rate with interest rate, nper with the desired period and pmt with the periodic amount

hope this helps

#### KenRossman

##### Senior Member
Thanks Howard...

I found the same formula in my SREA 201 workbook (that I took a million years ago).

I can't figure out what to do with the "^n"

IE: For say 16% and 24 months, what would be the steps for the 2nd month factor

1/(1+i/12)^n

1/(1+16/12)^n

1/(1+1.33333)^n

1/(2.33333)^n

?????

#### Howard Klahr

##### Senior Member
kenrossman said:
IE: For say 16% and 24 months, what would be the steps for the 2nd month factor

1/(1+i/12)^n

1/(1+16/12)^n

1/(1+1.33333)^n

1/(2.33333)^n

?????

Ken,

I need to first make a minor correction - when you substitute the interest rate into the formula you need to use the proper decimal point placement. Using you example 16% would be .16

1/(1+i/12)^n

1/(1+0.16/12)^n

1/(1+.0133333)^n

1/(1.0133333)^n

for the second month = 1/(1.0133333)^2
1/1.026844377 = 0.973857405

for the third month = 1/(1.0133333)^3
1/1.040535601 = 0.961043523

etc

#### KenRossman

##### Senior Member
So close, but still have no clue what ^2 or ^3 etc. means or how to key it on an hp12c????

Actually, I know ^2 & ^3 represents the 2nd and 3rd month's factors, but cant figure out how to apply them...

Last edited:

#### Howard Klahr

##### Senior Member
^n refers to exponents, so ^2 means to multiply the number by itself (i.e. - a x a), ^3 would be to multiply the number by itself twice (i.e. - a x a x a)

to enter exponents in the hp12c there is a key x^y

#### KenRossman

##### Senior Member
Thanks again Howard!

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