I'm afraid that --- at least as it stands at present --- if you are using the Free version (as I do) then formulas have been removed, and for the Paid they are (apparently) supposed to be there but do not work. Gulp 
See my discussions with @aleksandra_budnik on that topic, in https://forum.handsontable.com/t/after-loading-format-currency/448/18 and https://forum.handsontable.com/t/no-aftersetcellmeta-event-when-a-comment-is-created-1-8-1/858/7, amongst others....
I know they were removed somewhere at or after 0.26.0. You need to revert to something like 0.25.1 (which is what I use) if you still want formulas.
The last I heard from @aleksandra_budnik was that maybe the devs have had a change of heart and formulas might be reintroduced at a later date into Free after all (see specifically https://forum.handsontable.com/t/no-aftersetcellmeta-event-when-a-comment-is-created-1-8-1/858/8). Feel free to advise him if, like me, you think formulas really must be in a "spreadsheet" component, even a free version....
