After all digits of a positive integer are added (i.e. added horizontally), if the added value is greater than or equal to 10, the number obtained by adding all digits horizontally until the value is less than 10 is a number. In other words, a number is repeated as the sum of its numbers until its value is less than ten, and the value obtained is a few of this number. For example, the number of 548 17 is 7, because 5+4+8+ 1+7=25. If 25 is greater than 10, add it again. If 2+5=7, if 7 is less than 10, 7 is 548/0.
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1, arithmetic square root
Square root, also called quadratic square root, refers to the real number whose multiplication result is equal to [√] for non-negative real numbers, in which the square root belonging to non-negative real numbers is called arithmetic square root. Positive numbers have two square roots; 0 has only one square root, which is 0 itself; Negative numbers have no square root. For example, the square root of 9 is 3 Note: Sometimes the square root we say refers to the arithmetic square root.
2. Quadratic root
If the square of a number x is equal to a, then this number x is called the square root of a (also called quadratic root). In layman's terms, a number multiplied by itself equals another number. The original number is the square root of the multiplication number.
Baidu Encyclopedia-Several Roots