🇨🇺 Freddis Reyes Hernández

The 2012 World Cup

The Mental Calculation World Cup is the discipline's main international event, contested across a fixed set of tasks: addition, multiplication of large numbers, calendar dates and square roots, with additional surprise problems set by the organisers. Results are published by the organisers at recordholders.org.

In the 2012 edition Reyes won the multiplication event and took the Memoriad Trophy, awarded for the fastest calculation overall. He held the multiplication record from 2012 to 2016.

How he started

He told World Mental Calculation in March 2018 that he had come to the field sideways. He had played football and volleyball, and heard on television about the calendar calculation record set by another Cuban, Yusnier Viera. A friend pushed him to try it.

He worked out his own formula for calendar dates, the discipline that asks a competitor to name the weekday for any date in history, and by 2010 he held a world record in it. The Daily Beast published Alex Bellos's account of the world championship of mental arithmetic in June of that year, which is the closest thing the sport has to a general readership.

Speed over accuracy

His method for multiplication is cross multiplication, and his stated approach is unusually candid about the trade-off it involves. He aims for speed rather than a perfect score, and admitted in the same interview that he does not usually attempt all ten problems in a set and does not train much for accuracy.

That is a rational strategy in a scoring system that rewards the fastest correct answers, and it explains a personal best of 11.60 seconds for an eight-by-eight-digit multiplication: a calculation most people could not complete on paper in a minute.

Where Freddis Reyes is now

Still competing. World Mental Calculation reported that at Memoriad 2024, held in the United Arab Emirates, he took silver in multiplication, more than a decade after the World Cup victory that made his name.

His life outside competition is harder. In the 2018 interview he described work that was physically hard, said he was saving money, and said he was looking for a way to study mathematics outside the university system. The sources used here do not report his circumstances since.

Why mental calculation persists

Every argument for the sport has to survive one objection: a telephone does this faster and never makes a mistake. The answer the community gives is that the competitions measure something machines have made invisible rather than obsolete, namely how far human working memory and pattern recognition can be pushed under a clock.

It is also a sport with an unusually flat entry barrier. It needs no equipment, no facility and no federation licence, which is how a Cuban who started after a television programme could end up holding a world record and a trophy for the fastest calculation on the planet.

The discipline is also unusually transparent about its own claims. Results are published task by task with times attached, so an assertion about who is fastest can be checked against a table rather than taken on trust, which is not true of most memory feats that reach the press.