笨办法学python第3课

print("i will now count my chickens:")  #打印字符
print("hens", 25 + 30 / 6) #打印字符，且 计算25+30/6
print("roosters", 100 -25 * 3 % 4)  #打印字符且计算 %指的是相除之后的余数 既75/4余数3
print("now i will count the eggs:")  # #打印字符
print(3 + 2 + 1 -5 + 4%2 -1/4 + 6)  #计算
print("is it true that 3 + 2 < 5 -7?")    #在字符中判断，电脑会给出true 或者 false
print(3 + 2 < 5- 7)  #判断大小
print("what is 3 + 2?", 3 + 2)  #前面的是公式，后面会计算
print("what is 5 - 7?", 5 -7)  #前面是字符串，后面会计算
print("oh, that's why it's False")  #打印字符串
print("how about some more.")  ##打印字符串
print("is it greater?", 5 > -2) #前面有字符串，后面判断大小，系统会给true or false
print("is it greater or equal?", 5>=-2)  #相当于是大于等于号
print("is it less or equal", 5<= -2)  #相当于是小于等于号


运行结果
$ python3.6 ex3.py
I will now count my chickens:
Hens 30.0
Roosters 97
Now I will count the eggs:
6.75
Is it true that 3 + 2 < 5 - 7?
False
What is 3 + 2? 5
What is 5 - 7? -2
Oh, that's why it's False.
How about some more.
Is it greater? True
Is it greater or equal? True
Is it less or equal? False

练习题：
1. Above each line, use the # to write a comment to yourself explaining what the line does.（给每一行注释）
done
2. Remember in Exercise 0 when you started python3.6? Start python3.6 this way again and,using the math operators, use Python as a calculator.（像第0课中那样重新做一遍，把python作为计算器）


3. Find something you need to calculate and write a new .py file that does it.（找到需要计算的东西写一个新的文件）

4. Rewrite ex3.py to use floating point numbers so it’s more accurate. 20.0 is floating point.（
#重新做练习3，用带小数点的数字）

常见问题
1.%在python的运算符号中，代表着余数