...you accidentally turned the multi-tap function on. typically, if you press and hold the "#" key and then press the shift key, you enable a word editing feature that allows you to enter multiple numbers sequentially without having to press shift first (e.g. - like trying to type in a phone number without pressing shift after each number).

to turn it off, you need to go into options > language and change input language back to English (US) (as opposed to English (US - multitap)) or whatever you preferred language is.