运算

数的运算

1. How to add and subtract integers, decimals, fractions? What are the similarities in their calculation methods?

1. 怎样进行整数、小数、分数加减运算？它们的计算方法有什么相同点？

When adding and subtracting integers and decimals, the numbers in the same place should be aligned...

进行整数和小数加减时，相同数位上的数要对齐……

When adding or subtracting fractions, only the fractions are in the same unit...

进行分数加减时，只有分数单位相同时……

Similarities in addition and subtraction of integers, decimals, and fractions. It is the addition or subtraction of numbers in the same unit.

整数、小数和分数加减法的相同点。就是把相同计数单位的数相加或相减。

2. How to multiply and divide integers, decimals and fractions?

2. 怎样进行整数、小数、分数乘除运算？

Decimal multiplication and division can be converted to integer multiplication and division to calculate...

小数乘除法可以转化成整数乘除法来计算……

Fractional division can also be converted to component number multiplication...

分数除法也可以转化成分数乘法来计算……

3. What arithmetic laws have we learned?

3. 我们学过了哪些运算律？

We learned the laws of addition and multiplication.

我们学习了加法、乘法运算律。

4. According to the need to solve the problem, how to choose a reasonable calculation method?

4. 根据解决问题的需要，怎样选择合理的计算方法？

Mr. Wang wants to buy 190 copies of the Little Mathematics Dictionary. The unit price is 3.80 per copy. She has 800 yuan with her, is that enough? How much should I get back (or pay more)?

王老师要买190本《数学小词典》，单价是3.80/本。她带了800元钱，够吗？应找回(或再付)多少元？

Discussion and communication

讨论与交流

What is the relationship between the four operations?

●四则运算之间有什么关系？