the math seems to work fine. but you can only click the button once you have enough for the upgrade without the 99.9999% off. meaning when u do finally get to click that button you can buy about 50-60 of them at a time. so using a strategy to only go up in the intervals you need to get your next bonus seems to work best....
tho that could still mean days without buying something... or if your in the late parts of the game... weeks! Happy Fun Times!
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