I figured recently that my biggest strategy is halving and doubleing easily, such as for when I do 5 times, I halve and then times by ten, sounds complicated, but for me I can double and halve simple numbers quite easily. I also turn the numbers into fractured blocks in my head when I imagine them into fractions. I can be pretty good, though I still get mistakes at times due to my thinking being flawed on not easily tranlateable to others. I also have a weired thing where if I close my eyes and lift my head a little bit for some reason my calculative and focus ability increases and I can do things faster, looks strange to others though.
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Through dream I travel, at lantern's call
To consume the flames of a kingdom's fall