Prime-ET is a handy little spreadsheet that allows you to create a table of prime-factors and their exponents, and input an n value for an n-degree ET.

If your computer can read Excel^TM, download it here

The program calculates:

• the ratio, from the prime-factors and exponents
  
• the 'octave'-reduced Semitone (i.e., cents) value
  
• the nearest ET degree for the n-ET you chose
  
• the Semitone value for the ET degree
  
• the 'error' of the ET degree from the ratio

It's set up with primes of 2, 3, 5, 7, 11, and 13, but they may be changed to any number at all, including non-prime odd-factors, integer-factors, pi ...anything.

The ET I have in there is my current object of study, 144-eq. You may enter any number at all - I don't know up to what limit, but ***************

If 2 is used as a factor, it allows you to:

• 'octave'-reduce the ratio yourself
  
• enter fractional powers of 2 to compare other ETs

As an example of the latter, to enter the 12-eq 'perfect 5th', just enter in the '2' column*************:

      =7/12

Any plain number (including decimals) can just be entered as is, but for any exponent that uses a calculation (like the ET shown above), make sure to enter the equal sign first, otherwise Excel will think you're trying to enter a date when you enter the slash.

One glitch is that the 'ratio' column will show a fractional ratio for an ET or other 'irrational' value.

I formatted it that way purposely so that it would convert the prime-factors & exponents into ratios that look the way most people who use them are used to seeing them.

It's easily changed from the menu choice Format|Cells, or with a right-click on the mouse, with the same choice on the pop-up menu. It may be formatted as a decimal or a variety of other ways.

Feedback welcome. Enjoy!