Looking on my profile, I have a Quoin Upgrade Multiplier of 18.9x
However, the Quoin values don't appear to be multiplied by itself 18.9 times, or even by a value of 18.9 . . . . it doesn't even appear to be multiplied 1.189% (which would mean that each 100% upgrade is REALLY adding 1%, which is just nonsensical).
My current iMG quoin value is 23. Were it actually multiplied, it would mean the base value, factored to 18.9 (x^18.9), the base value is 1.180. If it were multiplied by 18.9, it would be x*18.9, it would put the base value at 1.217. I seem to remember the quoins being worth more than that even when I started as a newbie glitch. And if it were percentage (x*1.189) would have the base value = 19.34 . . and I remember them being lower than that last week before the upgrade.
SO which is it? Because at a minimum, the terminology is confusing, and its hard to understand whether to buy an upgrade when the terminology doesn't make sense at all. If I increase my quoin multiplier by 100% -- which is what the cards advertise -- it should DOUBLE THEIR VALUE. It hasn't done that for me, and it's hard to understand how it works in reality since that isn't the effect.