«اوريگامي روش ارائه‌ي اشكال است كه عمدتاً با خم كردن ماده‌ي مورد استفاده (كاغذ) حاصل مي‌شود».

اصل لغت «اوريگامي» در زبان ژاپني از «اورو» به‌معني خم كردن و «كامي» به‌معني كاغذ گرفته شده است. اما خم كردن كاغذ اسامي ديگري نيز در زبان ژاپني داشته است كه به‌تدريج به‌نفع اوريگامي از دور خارج شده‌اند.

Johann Martin Zacharias Dase (June 23, 1824, Hamburg - September 11, 1861, Hamburg) was a German mental calculator

The famous mathematician Carl Friedrich Gauss investigated his abilities. He recommended that the Hamburg Academy of Sciences should allow Dase to do mathematical work on a full-time basis, but Dase died shortly thereafter.

Dase multiplied 79532853 × 93758479 in 54 seconds. He multiplied two 20-digit numbers in 6 minutes; two 40-digit numbers in 40 minutes; and two 100-digit numbers in 8 hours 45 minutes. Gauss commented that he thought that someone skilled in calculation could have done the 100 digit example in about half that time with pencil and paper.

In 1844, Dase calculated π to 200 decimal places in his head, from the Machin-like formula

He also calculated a 7-digit logarithm table and extended a table of integer factorizations from 7,000,000 to 10,000,000.

The book "Godel, Escher, Bach: an Eternal Golden Braid" by Hofstadter mentions his calcluating abilities. "... he also had an uncanny sense of quality. That is, he could just "tell", without counting, how many sheep were in a field, or words in a sentence, and so forth, up to about 30."

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