Are what we in the US call run-on sentences OK in French? Are prices always written using numbers? Thanks!

Cécile, next time I spot a run-on sentence, I’ll send a message. I thought prices were always written in figures, too, but the lesson required quatre euros to be spelled out. Perhaps it’s because the customer was being told verbally the price.

In any event, I am learning! Thanks so much for an outstanding site. 

A run-on sentence means two or more sentences in a row without being separated by a coordinating conjunction (and, but, or, nor, so, for, yet) or by a semi-colon.  It's technically incorrect in American English but much more acceptable in British English.  An example would be.  "He is going she is not." I have seen many examples in French of run-on sentences; however, I am not sure if it truly is an error in French.)

(I teach English. A run-on sentence does not mean a rambling or very long sentence as many people think. Also, if you separate the sentences with "however," "therefore," "nevertheless," etc., that doesn't work either. If you are a strict grammarian (a "purist"!), you must always use a semi-colon or a coordinating conjunction to separate sentences.)