One is to calculate the maximum value;

The second is to calculate the minimum value;

The estimation method of addition and subtraction in the third grade of primary school is greater than 5 and less than 5. It can also be understood as rounding: 0, 1, 2, 3, 4, all without carry; Five, six, seven, eight, nine.

For example, Xiaoming's mother goes to the mall to buy vinegar and soy sauce. The price of vinegar is 17 yuan and the price of soy sauce is 12 yuan. Estimate how much money Xiao Ming's mother needs to bring. This should be estimated as follows: 17≈20,12 ≈10,20+10 = 30 (yuan).

A: Xiaoming's mother needs to bring 30 yuan money.

Extended data

1, truncation method: truncation method is a commonly used mathematical method, which removes the decimal part of a number and takes its integer part, and its value is approximate (that is, less than the exact value), which is often used in life.

2. Measurement unit estimation method: What is the size of the actual empirical data by using the real-life objects to perceive the measurement unit?