毕达哥拉斯定理就是勾股定理，指直角三角形两直角边的平方和等于斜边的平方，公式为 a2+b2=c2a2+b2=c2 。 这个定理是几何学中最基础的规则之一，用来计算直角三角形的边长关系，在中西方数学史上都有重要地位。
Φ is the twenty-first letter of the Greek alphabet, pronounced 'phi,' with an uppercase Φ and lowercase φ. The top left of the lowercase is usually open, and sometimes it is written as a smaller version of the uppercase shape. Besides being a letter, it represents various specialized meanings in different disciplines.
Arabic numerals are the ten digit symbols from 0 to 9 that we commonly use. Although called 'Arabic' numerals, they were actually invented by ancient Indians and later transmitted to Europe by Arabs, which is how they got this name. They are the number notation used worldwide today.
Eratosthenes (circa 275–194 BC) was a famous Greek mathematician, astronomer, and geographer, born in Cyrene, Libya. His most celebrated achievement was pioneering a method for measuring the Earth's circumference, calculating a result with less than 5% error, and he was the first to propose the term 'geography,' earning him the title of 'Father of Geography' in later generations.
The Sieve of Eratosthenes is an ancient algorithm for quickly finding all prime numbers within a certain range, proposed by the Greek mathematician Eratosthenes.
Albert Einstein was one of the greatest physicists of the 20th century, proposing the theory of relativity and the mass-energy equivalence equation, and he won the 1921 Nobel Prize in Physics.
'Bitwise method' usually refers to 'bitwise operation,' a low-level computational method that performs logical or shift operations on each binary digit of integers. It is not an independent 'number system' or 'numeral system' (the latter is often mistakenly called 'bitwise counting method').