First, multiples and divisors

Maximum common divisor: The common divisor of several numbers is called the common divisor of these numbers. There is a finite common factor. The largest one is called the greatest common divisor of these numbers.

Least common multiple: The common multiple of several numbers is called the common multiple of these numbers. There are infinite common multiples. The smallest one is called the least common multiple of these numbers.

Second, profit.

Interest = principal × interest rate × time (time is usually in years or months, which should correspond to the unit of interest rate).

Interest rate: The ratio of interest to principal is called interest rate. The ratio of interest to principal for one year is called annual interest rate. The ratio of interest to principal in January is called monthly interest rate.

Third, decimals

Natural number: an integer used to represent the number of objects, called natural number. 0 is also a natural number.

Cyclic decimal: a decimal, starting from a certain bit of the decimal part, and one or several numbers are repeated in turn. Such decimals are called cyclic decimals. Like 3. 14 14 14.

Fourth, the reciprocal of the score.

Find the reciprocal of the fraction, such as 3/4. Switch 3/4 numerator and denominator, so that the original numerator and denominator are the same. It's four-thirds. 3/4 is the reciprocal of 4/3, or 4/3 is the reciprocal of 3/4.

Verb (abbreviation of verb) Pi: The ratio of the circumference to the diameter of a circle is called Pi.

The quotient of the circumference divided by the diameter of the circle is a fixed number called pi. It is an infinite cycle decimal (irrational number), represented by the letter π. When calculating, we usually take its approximate value, π≈3. 14.