The title translates as “square root,” but Stromae’s second album is mostly interested in addition and multiplication. “Tous le mmes” fuses cabaret with EDM, and “Moules frites” blends rumba and South African choral melodies, while “Carmen” is a trap remix of the famous aria. The Belgian singer’s concepts are as ambitious as his production: The melancholy “Quand c’est?” tackles lung cancer, and “Humain l’eau” uses tribal beats to mock First World prejudice. Returning to his roots, the touching “Papaoutai” pays tribute to his late father, a victim of the Rwandan genocide.