Intrigued by math, he began keeping a running tally of his family's groceries at the store so his father could give the cashier an exact check before the total was rung up.

[3] Flansburg can mentally add, subtract, multiply, divide, and find square and cube roots almost instantly, with calculator accuracy.

[4] In 1991, he was involved in the creation of "The Human Calculator System", a product designed for direct-marketing salespeople, consisting of a study guide and four cassette recordings teaching his method.

In the spring of that year, he appeared on the infomercial show "Amazing Discoveries", hosted by Mike Levey, to promote his product.

[3] Flansburg is the creator of the Counting Bee, an annual, fast-paced competition to find the fastest human counters in different age categories around the world.

State-wide and country-wide competitions determine Counting Bee World Champions by age groups.

[7] He has been a presenter at organizations such as NASA, IBM, The Smithsonian Institution, the National Council of Teachers of Mathematics,[4] and the Mental Calculation World Cup.

On April 26, 2009, on the Japanese primetime show Asahi's Otona no Sonata, he broke his own world record with 37 answers in 15 seconds.

[11] He was featured as The Human Calculator in the first episode of Stan Lee's Superhumans, which aired on The History Channel on August 5, 2010.