There is this schism between people who prefer metric and people who prefer inches.
Metric people like nice convenient units, decimal, and being able to make easy calculations. Inches people like complicated fractional units.
So I have come up with a new ruler to unite the two. It has nice millimeter and centimeter sized increments, but uses inches as the scale.
I present to you, my new universal fractional ruler!
The centimeter and millimeter sized divisions are labeled with fractional inch units. To get this fairly close, without going too large on my fractions, why limit yourself to powers of two for the denominators? This ruler takes full advantage of the full power of fractions by varying not just the numerator but also the denominator.
For example, what would be "1 cm" in metric is 37/94 inches. 2 cm is 68/80 inches and 10 centimeters is 3" 89/95.
I originally had my computer find the closest fractions with a denominator up to 128, but 1/127" is exactly 0.2 mm, so the best fitting fractions were all in 127'th of an inch. That didn't make for interesting variety, so I limited the denominator to 99 instead.
All the millimeter sized divisions are labeled, though you may need a magnifier to read them. For example, 1 mm is 3/76". 2 mm is 7/89 and 3 mm is 11/93.
But you can still do calculations with these scales. People who use inches like it awkward that way, and this ruler excels at that!
Lets add the equivalent of 4 cm and 5 cm
We have 1" 50/87 + 1" 92/95
= 2" + 4750/8265 8004/8265
= 2" + 12754/8265 = 3" 4489/8265
Which is very close to the fraction at 9 cm, in fact, its within 0,000076". But that's using a decimal fraction, which is cheating. Its within 1/13126 of an inch.
Doing arithmetic with this scale, is even more fun than doing it on a regular fractional inch scale. cause why else would you use use inches? Some people like the mental challenge, why else do Just like people like doing soduku or crossword puzzles.
So I think this new scale will solve the metric/inches schism. It has nice sensible metric sized divisions, with even more beloved fractions that the inches fols love so much!
You can download a template for this new ruler here: