The addition symbol begins with the prefix p of the English plus sign. In Germany, the word "et" equivalent to English "and" is used. With the prosperity of European business, writing "et" is too slow. In order to speed up, the two letters are written together, so "et" gradually becomes "+".
The same is true of subtraction, which uses the prefix m of English MINUS sign, which is also convenient for sketching and gradually becomes "-".
Oughtred in Britain first used "×" as the multiplication symbol. It is said that multiplication symbols are derived from addition symbols. Multiplication is a special addition operation, so if the addition symbol "+"is slightly changed, it will become the current symbol "×".
The symbol "∫" for division was first used in Varis, England, and was later popularized in England. The horizontal line in the middle of the symbol separates the upper part and the lower part, which vividly shows the "points".
Extended data:
First, the essence of addition
It is exactly the same thing, that is, the repetition or accumulation of similar things, which is the beginning of numerical operation. Different kinds, such as an apple and an orange, can only be equal to two fruits, so there is a relationship between classification and classification.
Subtraction is the inverse operation of addition; Multiplication is a special form of addition; Division is the inverse operation of multiplication; Power is a simple form of multiplication; The root is the inverse operation of power; Logarithm is the law of finding power term; Derivative is developed from logarithm; Then differential and integral. The development of digital operation is a more special situation and a more repetitive law.
Second, the essence of subtraction
Subtraction is a mathematical operation that represents the operation of removing an object from a collection. Its symbol is the minus sign (? )。 For example, in the picture on the right, there are five? Two apples, five apples, two were taken away, leaving three apples. So 5? 2 = 3。 Subtraction is to remove or reduce physical quantities and abstract quantities with different objects (including negative numbers, fractions, irrational numbers, vectors, decimals, functions and matrices).
Third, the multiplication algorithm
The multiplication of integers meets the following requirements: commutative law, associative law,? Law of distribution, law of elimination.
With the development of mathematics, the object of operation has developed from integer to more general group.
Intra-group multiplication is no longer needed to satisfy the commutative law. The most famous noncommutative example is the quaternion group discovered by Hamilton. But the law of association is still satisfied.
1. Multiplicative commutative law: AB = BA. Note: letters are multiplied by letters, and the multiplication sign can be written without writing.
2. Multiplicative associative law: (ab)c=a(bc)
3. Multiplication distribution law: (a+b)c=ac+bc.
Fourth, the nature of division.
The dividend is enlarged (reduced) by n times, and the quotient is correspondingly enlarged (reduced) by n times under the condition that the divisor is unchanged.
The divisor is expanded (reduced) by n times, while the dividend is unchanged, and the quotient is correspondingly reduced (expanded) by n times.
Dividing by two divisors in succession is equal to dividing by the product of these two divisors. Sometimes simple operations can be performed according to the nature of the division. For example, 300÷25÷4=300÷(25×4) divided by a number is equal to the reciprocal of this number.
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