The operation of finding the product of n identical factors is called power, and the result of power is called power. In, a is called the base and n is called the exponent. When an is regarded as the result of the n power of a, it can also be read as the n power of a. ..

The odd power of a negative number is negative and the even power of a negative number is positive.

Any power of a positive number is a positive number, and any power of a positive integer is 0.

Operation sequence of rational number mixed operation:

(1) Multiply first, then multiply and divide, and finally add and subtract;

(2) the same layer operation, from left to right;

(3) If there are brackets, do the operation in brackets first, and then follow the brackets, brackets and braces in turn.

1.5.2 scientific counting method

Numbers greater than 10 are expressed as a 10n (where a is a number with only one integer and n is a positive integer), and scientific notation is used.

Use scientific notation to represent n-bit integers, where the exponent of 10 is n- 1.

1.5.3 divisors and significands

A number that is close to the actual number but still different from the actual number is called a divisor.

Accuracy: an approximate value is rounded to the nearest place, so it is accurate to the nearest place.

From the first non-zero digit to the last digit on the left of a number, all digits are valid digits of this number.

For the number a 10n expressed by scientific notation, its effective number is specified as the effective number in A. ..