1 Multiplication with decimals: Multiply the decimals of two digits, then multiply the single digits, and finally add the two results. For example, to calculate 23×45, you can first calculate 20×50= 1000, then calculate 3×5= 15, and finally add1000+15 =10.

2. Multiplication method: decompose a two-digit number into the sum of two one-digit numbers, then multiply with another two-digit number respectively, and finally add the two results. For example, if we calculate 23×45, we can decompose 23 into 20+3, and then multiply it by 45 to get 900 and 135 respectively, and finally 900+ 135= 1035.

3. Carry method: in the calculation process, if the result of a certain bit is greater than or equal to 10, it needs to be moved forward. For example, when calculating 23×45, if ten digits are multiplied to get 80, then the single digits need to go forward.

4. Grouping method: Divide two two-digit numbers into two groups, each group contains a ten-digit number and a single-digit number. Then calculate the product of each group separately, and finally add the two results. For example, when calculating 23×45, 23 can be divided by 20 and 3, and 45 can be divided by 40 and 5. Then calculate 20×40=800 and 3×5= 15 respectively, and finally calculate 800+ 15=8 15.

Advantages of India's two-digit multiplication:

1, efficient and fast: India's two-digit multiplication is to split two two-digit numbers into ten digits and single digits, then cross-multiply, and finally add the results to get the final product, which can make people multiply faster.

If you want to calculate 23 times 45, first split 23 into 20 and 3, and 45 into 40 and 5, and then cross multiply, that is, 20 times 40, 20 times 5, 3 times 40, 3 times 5, and finally add the results to get the final product. This method is faster than the traditional written calculation, especially in the era when there are no calculators and computers, and the efficiency is even more remarkable.

2. Wide scope of application: In addition to the basic two-digit multiplication, the principle of Indian two-digit multiplication can also be extended to three-digit or even four-digit multiplication. For example, the operation of 892×998: if it is a Chinese algorithm, it needs to be multiplied and added three times to operate this formula like the above example. However, if India's calculation method is adopted, the calculation efficiency will be obviously improved.

3. Mathematical thinking training: India's two-digit multiplication can help people better understand the essence of multiplication, thus improving mathematical literacy. It is not only an important part of ancient Indian mathematical culture, but also an important course of the development of human mathematical thinking.

4. Strong practicability: India's two-digit multiplication does not rely on any tools, and only needs paper and pen to complete the calculation, which is highly practical. This calculation method can be widely used in families, schools or workplaces.