The basic operation of decimal multiplication is to convert decimals into fractions and then multiply them. The algorithm is to expand decimals into integers; Calculate the product according to the law of integer multiplication; See how many decimal places there are in the factor. Calculate the decimal places from the right side of the product.

In the process of multiplying decimal by decimal, the reason is to convert decimal into fraction, multiply the fraction, then simplify the result and convert it back to decimal form.

The operation process of decimal multiplication is:

1, for the multiplication of two decimals, first convert them into decimal form, so that it is easier to calculate when the decimal is converted into decimal form.

2. When two fractions are multiplied, you can multiply the molecules of the two fractions to get a new molecule. Multiply the denominator of two fractions to get a new denominator. Simplify the new numerator and denominator, and subtract points if necessary.

3. Take the simplified numerator as the numerator of the new fraction and the simplified denominator as the denominator of the new fraction, that is, get the result of decimal multiplication.

For example, if you want to calculate 0.5 times 0.3, you can follow these steps:

1. Convert 0.5 and 0.3 into fractions: 0.5= 1/2, 0.3=3/ 10.

2. Molecular multiplication: 1×3=3. Denominator multiplication: 2× 10=20.

3. Simplified result: 3/20 cannot be reduced any more.

Teaching Design of Decimal Multiplication

1. Introduction: In the introduction part, students can be interested and think by asking questions or giving examples. Or show a real-life fractional multiplication problem. Guide students to think about the relationship between decimals and fractions and the relationship between decimal multiplication and fractional multiplication.

2. Concept explanation and demonstration: explain the concept of decimal multiplication, and explain that decimal can be converted into decimal form for multiplication. Demonstrate how to convert decimals into fractions and the steps of fractional multiplication by examples. Explain the concept of simplification and simplify the form of fractions.

3. Demonstration of calculation steps: provide a concrete example of decimal multiplication and demonstrate the calculation steps step by step. Emphasize the importance and significance of each step, such as converting decimals into fractions, multiplying numerators, multiplying denominators and dividing fractions.