In mathematics, "accurate to 0. 1" means that the calculation result keeps 1 decimal, and the second decimal is generally selected by rounding, that is, the second decimal is directly discarded if it is less than 5, and rounded if it is greater than or equal to 5. 1 decimal plus 1, which is "accurate to 0./"in mathematics.

(1) Rounding method: which bit to round to depends on the number after this bit. If it is 0, 1, 2, 3, 4, there is no need to go forward 1. (Sigong) If it is 5, 6, 7, 8, 9, it needs to go forward 1 (five decimal places). No matter which number is rounded, all numbers after that number can be rewritten as 0, or abbreviated form can be used.

(2) Keep the integer, that is, it is accurate to 10, and the mantissa after 10 is omitted. Keep one decimal place, that is, accurate to the tenth place, and the mantissa after the tenth place is omitted. Keep two decimal places, accurate to hundreds, omit the mantissa after hundreds, and so on.

(3) In the process of rounding and approximation, if the reserved digits are 0, this 0 cannot be removed, because although the decimal numbers are equal in size according to their nature, their accuracy is actually different.

(4) Approximation of "product" by rounding method: the correct product can be calculated first, and then the approximation can be obtained by rounding method.

(5) Find the approximate value of "quotient" by rounding method: Common law: Calculate the correct quotient, and then find the approximate value by rounding method.