1, small 1 times 2 plus 80 skill: this skill is suitable for calculating the square of 1 1- 19. Subtract this number from 10, then multiply the difference by 2 and add 80. For example, the square number of 13 can be calculated as follows: 13- 10 = 3, 3 * 2 = 6,6+80 = 86, then the square number of 13 is 86.
2. The skill of multiplying the first number by 2 plus 80: This skill is applicable to the calculation of the square number of 9 1-99. Subtract this number by 80, then multiply the number of heads by 2, and add 160. For example, the square number of 93 can be calculated as follows: 93-80= 13, 13*2=26, 26+ 160= 186, then the square number of 93 is 186.
3. mantissa multiplied by 2 plus 800 skill: this skill is applicable to the calculation of the square of 1-9. Multiply this number by 2 and add 800. For example, the square number of 5 can be calculated as follows: 5*2= 10, 10+800=8 10, then the square number of 5 is 8 10.
Ways to learn mathematics well:
1. Establish a good mathematical foundation: To learn mathematics well, you need to lay a good foundation and master the basic concepts, principles, formulas and theorems of mathematics. In order to build a solid foundation, students should pay attention to classroom listening, finish their homework carefully, read more textbooks and reference books, do more exercises and firmly grasp the basic knowledge.
2. Cultivate mathematical thinking ability: Mathematics is not only a discipline, but also a way of thinking. Learning mathematics well needs to cultivate one's mathematical thinking ability, including logical reasoning, inductive classification and reduction. Students can exercise their thinking ability by doing some thinking training questions and questions, at the same time, they should pay attention to the understanding and application of new knowledge points, and form their own ideas and methods for solving problems.
3. Practice more and communicate more: Mathematics is a practical subject. Students can improve their practical ability by solving practical problems, participating in math competitions and organizing math groups. At the same time, math communication with classmates, teachers and netizens is also a good way to improve math ability. You can learn from each other, share experiences, discuss problems, and constantly broaden your mathematical horizons and ideas.