The Guardian‘s science section reports on a new numbers game, “Flash Anzan.” It’s based on the Japanese abacus, or soroban, which a million Japanese kids learn to use every year. The game requires mental representations of an abacus; the game, according to author Alex Bellos, goes like this:
. . . 15 numbers are flashed consecutively on a giant screen. Each number is between 100 and 999. The challenge is to add them up.
Simple, right? Except the numbers are flashed so fast you can barely read them.
Takeo Sasano, a school clerk in his 30s, broke his own world record: he got the correct answer when the numbers were flashed in 1.70 seconds. In the clip below, taken shortly before, the 15 numbers flash in 1.85 seconds. The speed is so fast I doubt you can even read one of the numbers.
Apparently they flash different sets of numbers at different rates, and the winner is the one who gets the right answer first at the fastest flashing rate.
Amazing. Here’s another clip,
. . . showing Sasano break the world record at 1.80 seconds. Note that the format of the competition is a bit like an arithmetical version of a spelling bee. The remaining contestants are sitting in chairs. The numbers are flashed. The contestants write down their answers and exchange papers for marking. The result is displayed on the screen, and those who got the correct answer stand up.
How does it work? Bellos explains more, but go over to his piece to see a bunch of other interesting stuff and one other amazing video in which the mental addition is done simultaneously with a word game.
Anzan was invented a few years ago by an abacus teacher, Yoji Miyamoto, who wanted to design a maths game that was only solvable by calculation with an imaginary abacus, a skill known as anzan.
When the contestant sees the first number he or she instantly visualizes the number on the imaginary abacus. When they see the second number they instantly add it to the number already visualized, and so on. At the end of the game the contestants cannot remember any of the numbers, or the intermediate sums. They only retain the final answer on the imaginary abacus.
Performing arithmetic using an imaginary abacus is the fastest way to perform mental calculations.