how   
ahoana
how? What? Used in answering a call. Why? What is the cause of it? It is also an exclamation, as ahoana ary! Well then! It admits of the suffix pronouns and tenses: ny faty aza ahoako: I care not for, or I trouble not myself about death; death has no fear for me! ~ ahoanao izany?: what is that to you? [Richardson 1885]
why? how? [Hallanger 1973]
aiza
where? Whither? In what place? How? When followed by No it means, by what means? See aia. [Richardson 1885]
akory
how! How great! as, akory lahy ny fahabetsahan' ny olona! How numerous are the people! [Richardson 1885]
how is that? [Hallanger 1973]
firy
how many? How often? [Mal. piro.] [Richardson 1885]
how many? [Hallanger 1973]
hafiriana
how many days? [Richardson 1885, Hallanger 1973]
hoatrinona
how much ? how many ? [Hallanger 1973]