I am using three different options:

1) In any page you can integrate Unicode math symbols. So, for simple inline symbols you can do just copy-paste from a side with a Unicode math symbol collection like Wikipedia: https://en.wikipedia.org/wiki/Mathematical_operators_and_symbols_in_Unicode (there are many out there, or also Word docs where you can just copy-paste it). This is recommended for simple single symbols in inline text. The 2ᵏ is an example for that.

2) When you do not want to do copy-paste all the time, use a plug-in for the browser like TeX to Unicode for Chrome. So, if you are familiar with TeX symbols, you can use LaTeX symbols in the browser.

3) But when I am integrating more complex formulas like in the text here, I directly integrate an image. I am generating the needed formula or expression in LaTeX. Then, I open the generated pdf-File on 130%, and take a snapshot of the corresponding formula e.g., with Snip & Sketch which is available with Microsoft, and I save it as an image. Why I am doing it in that way? I found out that 130% corresponds to more or less the font size on Medium.com. Taking a snapshot in that way gives a good quality that adjusts well when reading the text on different devices. And I am used with LaTeX. So, it is the fastest way for me to write formulas. It is for me the best trade-off between quality and efficiency.