Unsolvable

In its original American broadcast, "Unsolvable" was seen by an estimated 2.50 million household viewers and gained a 1.1/3 ratings share among adults aged 18–49, according to Nielsen Media Research.[1] This was a slight increase in viewership from the previous episode, which was watched by 2.49 million viewers with a 1.2/3 in the 18-49 demographics.[2] This means that 1.1 percent of all households with televisions watched the episode, while 3 percent of all households watching television at that time watched it. With these ratings, Brooklyn Nine-Nine was the second most watched show on FOX for the night, behind Glee, fifth on its timeslot and eleventh for the night, behind Glee, Marvel Studios: Assembling a Universe, The Goldbergs, Person of Interest, Growing Up Fisher, Chicago Fire, About a Boy, NCIS: Los Angeles, NCIS, and The Voice.

"Unsolvable" received mostly positive reviews from critics. Roth Cornet of IGN gave the episode a "great" 8.5 out of 10 and wrote, "Another strong showing from the B99 team as we head towards the Season 1 finale. To some degree, the focus has been on Boyle and Peralta's romantic woes over the last couple of weeks, and I assume that will play a big part in the closer."[3]

Molly Eichel of The A.V. Club gave the episode a "B+" grade and wrote, "'Unsolvable' combines those two spheres — workplace comedy and the cop show—exceedingly well. Other episodes have done so, and done it well, but 'Unsolvable' in particular feels like a mature episode structurally. The major plot arcs — namely Boyle's possible move to suburban Ottawa with fiancé Vivian and Peralta's long-simmering crush on Santiago — largely stay stagnant. That's totally okay. Both ideas are touched upon in order to create their own self-contained narratives, and there's only so much movement that can happen before their inevitable end, and Brooklyn Nine-Nine needs to save something for the final two episodes. Yet, 'Unsolvable' feels like the work of a show mature enough to move into an even more confident second season than its already thoroughly enjoyable first."[4]

Andy Crump of Paste gave the episode an 8.8 and wrote, "After the gang took a break from busting crooks, following up on leads, or doing anything remotely resembling police work last week in 'Fancy Brudgom,' they’re back—well, most of them, at least — to acting like they're cops with 'Unsolvable,' which means that all of the heartfelt, character-oriented goodness that's come to define the series' overarching quality gets pushed aside in favor of hilarity in law enforcement for most of the episode."[5]