There is no doubt that "estimation method" is the first fast calculation method in data analysis, and whether it can be estimated first must be considered before all calculations are made. The so-called estimation is a fast calculation method of rough estimation under the condition that the accuracy requirement is not too high, which is generally used in the case of large difference in options or comparison data. There are many ways to estimate, which require candidates to train and master more in actual combat.
The premise of estimation is that the difference between the options or the numbers to be compared must be large, and the size of this difference determines the accuracy requirements for "estimation".
The second skill of fast calculation: direct division
"Direct division" generally includes two forms in terms of questions:
First, when comparing multiple scores, the maximum/minimum number in the first place is the maximum/decimal number in the case of equal quantity;
Second, when calculating the score, you can choose the correct answer by calculating the first place under different options.
"Direct score" is generally divided into three gradients according to the difficulty:
First, you can simply and directly see the first business place;
Second, you can see the first place of quotient through hands-on calculation;
Third, for some complicated scores, the first place of the "reciprocal" of the score needs to be calculated to determine the answer.
The third quick calculation skill: truncation method
The so-called "truncation method" refers to a fast calculation method that "truncates the numbers in the calculation process within the precision range (that is, only look at or take the first few digits, so as to get the calculation results with sufficient accuracy". When using "truncation method" in addition and subtraction, add and subtract directly from the upper left bit (and pay attention to whether the next bit needs carry and dislocation) until you get the answer with required accuracy. When using truncation method in multiplication or division, we need to pay attention to the direction of truncation approximation in order to make the result as accurate as possible.
The fourth quick calculation skill: the same method
The so-called "similarity method" refers to a fast calculation method that "when comparing the sizes of two fractions, the numerator or denominator of these two fractions are the same or similar to simplify the calculation". Generally includes three levels:
First, make the numerator (denominator) exactly the same, so you only need to look at the denominator (or numerator) again;
Two, after the numerator (or denominator) is similar, there is a situation that "the denominator of a fraction is larger, the numerator is smaller" or "the denominator of a fraction is smaller, the numerator is larger", so the size of two fractions can be directly judged.
The fifth quick calculation skill: difference method
One-minute quick calculation tips:
"Difference method" is a quick calculation method when comparing the sizes of two fractions, and it is difficult to solve it by other quick calculation methods such as "direct division" or "identical method".
The sixth quick calculation skill: interpolation method
"Interpolation" refers to a fast calculation method of "reference comparison" with an intermediate value when calculating numerical values or comparing large and small numbers. Generally speaking, it includes two basic forms:
First, it is relatively difficult to compare the sizes of two numbers directly, but there is obviously a number between the two numbers that can be compared and easily calculated, so the size relationship between the two numbers can be quickly obtained from the intermediate number. For example, the comparison between a and b, if a number c can be found, and A >；; C, and b < C, that is, you can judge A> B.
Secondly, when calculating a numerical value F, it is difficult to judge two close numbers A and B, but we can easily find a number C between A and B, such as A.
The seventh skill of fast calculation: rounding method
"Rounding method" refers to the process of calculating the intermediate result into an "integer" (whole hundred, whole thousand and other convenient calculation forms), thus simplifying the quick calculation method of calculation. "Rounding method" includes addition and subtraction rounding and multiplication/division rounding.
The eighth skill of fast calculation: scaling method
"Scaling method" refers to a fast calculation method that can boldly "scale" (expand) or "shrink" (shrink) the intermediate result in the comparative calculation of numbers, so as to quickly get the size relationship of the numbers to be compared.
Quick calculation skill 9: growth rate correlation speed algorithm
Key points: Calculating the data related to the growth rate is a common problem in data analysis, and there are some common quick calculation skills for this calculation. Mastering these quick calculation skills is very important for quickly answering data analysis questions.
Quick calculation skills 10: comprehensive speed algorithm
Key points: The "comprehensive speed algorithm" contains many quick calculation methods. Although it is not as good as the first nine quick calculation skill systems in our data analysis problem, these quick calculation methods are still effective means to improve the calculation speed.