Actually, the recorded literacy rate is 86% in the USA[0]. The only number I can find for numeracy is this study [1], and depending on whether 'level 1' is considered numerate, it seems to show that between 5% and 20% of the US population is innumerate.

[0] - http://www.statisticbrain.com/number-of-american-adults-who-... [1] - http://skills.oecd.org/documents/SkillsOutlook_2013_Chapter2..., p75