An ASX listed but US-centric "digital banking platform" is spruiking small steps, and massive plans, in the vast American retail banking market.With origins in Brisbane but based in Los Angeles, ChimpChange yesterday set out data in a roadshow on inroads among its millennial target market.ChimpChange put customer acquisition via Facebook during the month of December at 55 per cent and Instagram at 14 per cent.It said customer numbers exceeded 45,000 at the end of December 2016, roughly double the level in September and more than four times the level at the time of its IPO and listing in July.Customers sign up via the ChimpChange app (one out of reach of curious Australian investors) and also receive a pre-paid MasterCard debt card. Deposits are held by Central Bank of Kansas City, though in aggregate these are small beer at around US$5 million.An investor presentation yesterday set out a "medium-term target", by 2018, to multiply gross revenue 50-fold to US$14 million from its present level of US$340,000.