1. The multiplication formula of 5 is listed by using the method of five-step addition, and the multiplication formula of 5 is compiled according to the formula.

The multiplication formula * * * of 2.5 has 9 sentences, and the difference between the results of every two adjacent formulas is 5, so the number of digits of the result is either 5 or 0.

3. Formulation method of the formula: The first half of the formula represents two multiplied numbers, and the second half is the product of multiplication. For example: four, five, twenty (four, five: multiply two numbers; Twenty: product of multiplication)

4. Key point: You can only write a multiplication formula according to 5: 5: 25.

Two, two multiplication formula

1. List the multiplication formula of 2 by adding two, and calculate the multiplication formula of 2 according to the formula.

2.2 The multiplication formula * * * has 9 sentences, and the difference between the results of every two adjacent formulas is 2.

3. Important note: The results calculated by applying the multiplication formula of 2 are all even numbers.

Three, three multiplication formula

1. Compile the multiplication formula of 3 according to the compilation method of the multiplication formula of 2.

2.3 The multiplication formula * * * has 9 sentences, and the difference between the results of every two adjacent formulas is 3.

3. Important: Only one multiplication formula can be written according to "two times two to get four" and "three times three to get nine".

Four, four multiplication formula

1. First get the result by counting, then list the multiplication formula, and calculate the multiplication formula of 4 according to the multiplier and the result.

2.4 The multiplication formula * * * has 9 sentences, and the difference between the results of every two adjacent formulas is 4.

3. Important note: The result calculated by applying the multiplication formula of 4 is even.

The application of verb (verb's abbreviation) 2~5 multiplication formula

1. Using the multiplication formula of 2~5, the related multiplication formula can be calculated.

2. Emphasis: According to the characteristics of the numbers given in the question, determine which formula to use for calculation.

Six, using the multiplication formula to solve the problem

1. Learn to collect, select and sort out mathematical information, and use the collected mathematical information to ask and solve problems.

2. Emphasis: Mathematical problems consist of two parts: known conditions and problems.