Full_Name: Will Gray Version: 2.7.0 OS: GNU/Linux (Debian) Submission from: (NULL) (160.129.18.69) The schoolmath package has several inaccuracies in it. Here is just a sample of some ways to get prime numbers between 1,000,000 and 1,000,100. Each method returns a different set and each result contains non-primes. data(primlist) (a <- primlist[primlist > 1000000 & primlist < 1000100]) (b <- is.prim(a)) which(!b) (c <- primes(1000000,1000100)) (d <- is.prim(c)) which(!d) Even the example for the function 'primes' gives some bad results. example(primes) -> x (y <- is.prim(x$value)) which(!y) I've tried contacting the maintainer(s) to let them know, but have not received a reply. In the meantime, I suggest this package be removed from CRAN.