I use xrp becouse It's top coin and If It's under 1$
There is not much lower to go.
AT the time the btc was 30k the xrp was 0.70
0.70 of 1$ is 30% correction. By this I know we got the lowest point to entry again.
U got point?
I see his point. It's easier for him because it's a low whole number. If there will be a coin that was valued at $10 he can also use that as basis or if there is another at $100 then it will be the easiest of them all. Dumped at $60 then it means 40% correction.
That's sounds a bit foolish but if it works out for him then why not. But its not a financial or trading advice.
You can just use the calculator pressing windows+R then type in "calc".

I'll be looking forward for an extended explanation and I hope it will be easier.