jcjenks advice is sound.

In fact, the accent circonflexe was removed from this word in the French spelling reform of 1990. This must be why Duolingo accepts it.

I don't know how the other spelling reforms have caught on, but this one is definitely not popular. I know teachers didn't like being told not to mark "coute" as incorrect.

Information about the reforms here: http://www.orthographe-recommandee.info/regles4.htm.

(@Sitesurf. Yes, accents can be clues about the etymology of a word and can often help anglophones see cognates. I think, however, that keeping them just for that is daft. This is not something I would say in French company just yet... )

I like accents where they help with pronunciation. The é is my friend, and as fast to type on a QWERTY keyboard as on an AZERTY, that is Alt Gr followed by e for é, or E for É.

The reforms are not totally dead. When someone in her early 20s proofread a form for me, just two weeks ago, she pointed out that my spelling of "porte-monnaie" was old-fashioned. The new alternative spelling was not in the 2009 dictionary I use. Young people seem to use the dashes-between-digits for numbers.

Some years ago there was a survey about the effect of the reforms. One of the questions was about "coute" and the percentage of French people who knew about it was 3.3%. None knew about the suggested change of "oignon" to "ognon".

Edit: Found reference to 2002-2003 survey. .Modified paragraph above slightly. http://fr.wikipedia.org/wiki/Rectifications_orthographiques_du_fran%C3%A7ais_en_1990#Diffusion

No, you should have the accent circonflexe above the u, "coûte."

Thanks, jcjenks and Mizotte. V. interesting. duolingo does not consistently require forms w/ and w/o the circumflex in this person of the pres. indic., as it did in this case. Very VERY interesting that there was a spelling reform. I'd never heard of it. Thanks much for the reference.

Wow, thanks for that link, Mizotte. C'est très intéressant !

You're right Mizotte, the French love reforms only not to respect them. However, I have never heard of removing accents circonflexes, more about funny things like 'nénufar' instead of 'nénuphar... (waterlily). The 'accent circonflexe' on the 'u' in 'coûte' comes from a contraction of 'couste' in old French (sounds more like 'cost', doesn't it?). Same story with 'bâtir' (build), 'tête' (head) or 'hôtel'.

What's with the e? Sometimes it's there as circonflexe in "coute", sometimes not. Why? What's the rule?