"אנחנו חייבים ללמוד הרבה נוסחאות."

Translation: We must learn lots of formulae.

[esdrujula69]

<3 DuoLingo for using formulae. Complaining about this would be like complaining if Duo's answers were phrased like "the bank in which i keep my money" and not "the bank i keep my money in". Nothing wrong with teaching people a slightly more formal and technically correct form

[joe648745]

Agreed. Now to feed my octopi in their loci.

[TeribleT]

Anachnu chayavim lilmod harbe nuscha'ot¹

¹ Can someone confirm if this is correct? Thank you in advance!

[XeroStomus1]

כמובן! אתה ילדה חכמה!

https://www.pealim.com/search/?q=%D7%A0%D7%95%D7%A1%D7%97%D7%90%D7%95%D7%AA

[Hadassah277241]

Formulae? Seriously? (And Duo marks me wrong for using Hebrew that is perfectly correct but not commonly used...)

[gsazbon]

Is not חייב an obligation, requirement and not a need?

[VivekRaman7]

The singular is spelt נוּסחָה but the plural adds an alef i.e.
נוסחאות

Don't think I've seen this before.

[danny912421]

דוגמה - דוגמאות

סיסמה - סיסמאות

There are many such examples, also in this course. Maybe you just never noticed.