Before and after digit method: This method requires students to find the nearest 10 digit or 100 digit, and digitize others to zero. For example, about 73 to 70 and 89 to 90.
Adjustment method: students can adjust the numerical value according to the size of the numerical value to facilitate calculation. For example, approximately 87 to 80 and 104 to 100.
Rounding method: This method requires students to round the value to the nearest integer. For example, about 74 to 70 and 95 to 100.
Simplification: Students can approximate a numerical value by simplifying some parts of the numerical value. For example, about 48 to 50 and 156 to 150.
These approximate methods can help students to provide close answers when calculating or estimating numerical values quickly. Through practice and practical application, students can gradually master these methods and be more flexible and accurate in solving problems.
Here are some examples:
Example: Estimation Addition
Question: Approximate value: 37+24.
Approximation method: adjustment method
Answer: about 37 to 40, about 24 to 20, and then calculate 40+20 = 60.
Approximation: 60
Example: Estimation Subtraction
Question: Calculation Approximation: 89-46
Approximation method: front and back digit method
Answer: approximate 89 to 90, approximate 46 to 50, and then calculate 90-50 = 40.
Approximation: 40
Example: Estimation Multiplication
Problem: Calculation Approximation: 6 × 8
Reduction method: simplification method
Solution: approximate 6 to 5, 8 to 10, and then calculate 5 × 10 = 50.
Approximation: 50
Example: Evaluation Department
Question: Calculation approximate value: 63 ÷ 9
Approximation method: rounding method
Solution: approximate 63 to 60, 9 to 10, and then calculate 60 ÷ 10 = 6.
Approximation: 6
These examples show how to use the divisor method to estimate values. Please note that approximation is not an exact answer, but it can help students get a close result quickly. With the accumulation of practice and experience, students will be able to better use the divisor method.