How many young trees are there in the fifth volume of the mathematics textbook published by Beijing Normal University? How many trees are there in a bundle of four trees? How about five bundles? 20×4=80 (tree) 20×5= 100 (tree). Answer: 4 bundles of 80 trees, 5 bundles 100 trees.

In the content before math oral division in grade three, the multiplication formula in the table is mainly used to solve the oral calculation of integer and hundred-digit integer divided by one digit.

As long as two of the laws are mastered, this kind of oral calculation is very convenient. Among them, the method summarized by Mr. Tang is a good choice for improving the operation speed in the process of oral calculation.

Starting from the two digits of the dividend, divide the two digits into integer ten digits, and divide the one digit into one digit of the dividend, and then divide by the quotient and quotient to get the final result.

This oral calculation method of division formula can promote students' sensitivity to numbers and the application of calculation methods, especially for improving mathematical thinking and expanding mathematical learning ideas.

The oral calculation method of dividing two digits by one digit (each digit of the dividend can be exactly divided): treat two digits as integer tens and one digit, divide the integer tens and one digit by one digit respectively, and then add the quotients of the two divisions.

Of course, in order to better remember the formula of dividing two digits by one digit, students can remember the calculation method through the following jingle formula to increase their interest in learning. Divide the number first, and then divide it by zero in turn. The composition of the number cannot be forgotten. Finally, return to zero and lose weight, and divide it in the table.

In the division formula of digits divided by one digit, when calculating orally, the ten digits and the single digits of the dividend are separated, divided by one digit respectively, and then the obtained quotients are added to get the final result. If you want to make the operation faster, it is suggested that students distinguish the ten digits from each digit in the calculation, which will make the calculation more efficient.