变量是指在一个过程或系统中数值或状态可以发生改变的量，在不同领域有具体的含义和应用 。
表达式简单来说就是由数字、符号、变量和括号拼起来的算式，用来算出一个结果或表示某种关系 。它最早在 20 世纪 30 年代由阿隆佐·邱奇等人系统化研究，现在广泛用于数学计算和计算机编程中 。
Any nonzero number raised to the power of 0 is equal to 1, while 0 raised to the power of 0 is meaningless. The formula is a^0 = 1 (a ≠ 0).
π is the fixed value obtained by dividing the circumference of a circle by its diameter; this ratio is the same for circles of any size. π is the symbol for the circle constant, representing the ratio of a circle's circumference to its diameter, approximately equal to 3.1415926535.
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.