Off-topic, but anyone knows where to buy such [1] old but not rare (so they are cheap enough) math books? In UK and globally? Is e-bay and perhaps amazon the best place? How to avoid fakes?
Like FooBarBizBazz says below. One can buy and sell multiple options at the same time such that the trade overall makes money if the price stays within a range or (with a different set of option trades) makes money if the price goes outside a range, regardless if it is up or down. Search for straddle and strangle options. Option trading for Bitcoin and all major crypto currencies is possible and it is where the majority of trading happens.
"Reverse collar" (aka "long (iron) condor") options strategies would be one possibility, depending on the premiums people are charging. This is assuming that options trading for Bitcoin is possible and works the same as options trading on the ordinary stock market. Also, I am not an options trader.
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Not an eink tablet, but Samsung Notes app on Samsung tablets do exactly this. It lets you search your handwriting without converting the handwriting into text first.
