python有四种类型的数字：
1.整型
a = 2 print a
2.长整型
b = 123456789 print b
3.浮点数
c = 3.2e2 print c
4.复数 复数为实数的推广，它使任一多项式都有根。复数当中有个“虚数单位”j，它是-1的一个平方根。任一复数都可表达为x+yj，其中x及y皆为实数，分别称为复数之“实部”和“虚部”。
d = (2+3j) print d
计算示例：
每种程序语言都有数学计算方法，数学符号通用，大家都知道。直接上代码吧：
print i will now count my chickens: print hens, 25 + 30 / 6 print roosters, 100 - 25 * 3 % 4 print now i will count the eggs: print 3 + 2 + 1 - 5 + 4 % 2 - 1 / 4 + 6 print is it true that 3 + 2 = -2 print is it less or equal?, 5 <= -2
运行结果应该是这样的：
root@he-desktop:~/mystuff# python ex3.py i will now count my chickens:hens 30roosters 97now i will count the eggs:7is it true that 3 + 2 < 5 - 7?falsewhat is 3 + 2? 5what is 5 - 7? -2oh, that's why it's false.how about some more.is it greater? trueis it greatet or equal? trueis it less or equal? false
eg：用数学计算把英寸和磅转化为厘米和千克。
1英寸 = 2.54厘米，1磅 = 0.4536千克
my_height_centimeter = my_height * 2.54 my_weight_kilo = my_weight * 0.4536 print he's %d centimeters tall. % my_height_centimeter print he's %d kilos heavy. % my_weight_kilo