My current target is 2260% as that would give me a bonus for every 4 KEM. I should hit that before the end of this month.
As a fellow freemium player here. My suggestion is that you need to reinvest as much as possible to build up your multiplier as fast as possible. We don't get interest on money in the bank do make value out of it when you get it. Spend spare money on more KEM, spare donuts on more multiplier, that way you earn more on the next dollar. The results are exponential. In the last 87 days I've added about 1200%. Growing at 27% a day. Reinvest!