1. Rounding 10 and 100: Break a number into parts that are easier to calculate, for example, break 25 into 20+5 and 36 into 30+6.
2. Oral formulas: By memorizing some specific oral formulas, you can quickly perform operations such as multiplication and division. For example, the formula of 13 multiplied by 15 is "head to head, tail to tail, tail to tail", that is, 1* 1= 1, 3+5 = 8,3 * 5 =15.
3. First and last combination method: If the first and last digits of two numbers are the same, then their product can be calculated quickly. For example, the formula of 1 1 multiplied by 1 1 is "the same from beginning to end", that is,11*1=12/.
4. Method of combining the last digit with the first digit: If the last digit and the first digit of two numbers are the same, the product of them can be calculated quickly. For example, the formula of multiplying 22 by 22 is "the same at the end", that is, 22*22=484.
5. Method of multiplying 1 1 by any number: If a number is a multiple of11,it can be quickly calculated by a specific oral calculation method. For example, the formula of 1 1 multiplied by 23 125 is "falling from the beginning to the end, and pulling down in the middle", that is, 2+3 = 5,3+1= 4,1+2 = 3,2+5 =
These methods can help students improve the speed and accuracy of oral calculation and reduce calculation errors. By practicing and applying these methods, students can better grasp the basis of mathematics and improve the learning effect.
After the oral calculation is completed, you can quickly check whether it is correct:
Step 1: Open the QQ browser, click the camera icon on the right side of the search box, and click Scan King.
Step 2: Enter the Scan King page and select Homework → Dictation and Correction.
Step 3: Wait a moment for the test questions, and then export the answers.