Yusnier Viera (born April 26, 1982) is a Cuban American mental calculator.

In early 2014, he participated in the Latin American show "Super Cerebros", of NatGeo.

Due to his extraordinary skills, University of Sussex neuroscientists took fMRI scans of his brain.

[5] In the study, he also completed a computerized version of the Raven's Progressive Matrices Test with an IQ score of 157 (standard deviation of 15).

Recently, he published the books Basic Course of Mental Arithmetic and Master the Multiplication Tables.