Basically, 'math' is quite complicated in ebooks (and a bit in html, too).
Depending on 'your math', you might have to include mathjax.
The problem is that many ebook readers do not support mathjax, and you might need to include (a downsized) javascript in you book since the original is too big.
After a lot of fuss, I managed to get this working (in a few readers):
https://github.com/espenmn/medialog....bok/MathJax.js
Another option would be to convert all the math to images.
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To covert word math to 'something you can use on the web', I use Mathtype