Came up with an interesting way to calculate your DPI

I recently tried to calculate my sensitivity by my dpi and leaving the sensitivity for modern warfare II on 1. I had 120 FOV and changed the dpi on my mouse until it did a complete 180 for a full swipe of my mouse. I found that different mice had different cm/360 than 90. So I divided the actual number, 90, by the calculated number- say, 89.94. Then I multiplied the dividend by my actual dpi by my mouse's set dpi and pasted the result in the dpi portion of the mouse calculator until the calculated result was 90. the result I came up with is 1 Sens 1539.3945 DPI. So I tried this with other mice. My g pro superlight with HyperGlides says 1950 but calculated 1539.3945 DPI, and each time I changed my mouse's set dpi until I got 180, sometimes using RawAccel, until it did a full 45 cm/180. And at that point I knew I then had 1539.3945 DPI. I calculated the dpi not by changing the sensitivity but by keeping the sensitivity the same and doing it backwards by changing the dpi until it truly matched an entire mousepad swipe by 45cm. I ignored the preset dpi and went only by the cm/180. and when I had that, I had 1539.3945 dpi.