rocket scientist, you don't have to be a

you don’t have to be a ˈrocket scientist (to do something)

,

it doesn’t take a ˈrocket scientist (to do something)

used to emphasize that something is easy to understand: Of course this model sells more than the others — it’s the cheapest! It doesn’t take a rocket scientist to work that one out.
See also: have, rocket, scientist

rocket scientist, you don't have to be a

This problem or idea is not that difficult to understand. This hyperbolic colloquialism dates from the mid-twentieth century, as does its synonym, you don’t have to be a brain surgeon. Clearly they imply that these professions require unusual intellectual acumen. Reporting on an economic forum, the Boston Globe quoted former President Bill Clinton, “You want to save 4 million lives? Give them the medicine. It’s not rocket science” (Jan. 28, 2005). Also, “And then he got murdered. Doesn’t take a rocket scientist to figure there’s a lot more to it than I thought” (David Baldacci, Hour Gam, 2004). See also no-brainer.
See also: have, rocket