Just to point out: these days you don't have to use the dosbox/qbasic combo in order to have a qbasic-compatible environment. There is an open-source implementation called qb64 that is both qbasic compatible and cross-platform (Windows, Linux and Mac).
Also, in qbasic, line number is optional. With SUB and FUNCTION, you can actually do structured programming like what other programming languages such as Pascal does.
Also, in qbasic, line number is optional. With SUB and FUNCTION, you can actually do structured programming like what other programming languages such as Pascal does.