Let us try to solve Fibonacci series. In this series we get the next number by adding the previous two numbers. So the series looks like 1,1,2,3,5,8,13 .......

#!/usr/bin/env python
a, b = 0, 1
while b < 100:
    print b
    a, b = b, a + b

The output

[kd@kdlappy book]$ ./fibonacci1.py
1
1
2
3
5
8
13
21
34
55
89

In the first line of the code we are initializing a and b, then looping while b's value is less than 100. Inside the loop first we are printing the value of b and then in the next line putting the value of b to a and a + b to b in the same line.

If you put a trailing comma in the print statement , then it will print in the same line

#!/usr/bin/env python
a, b = 0, 1
while b < 100:
    print b,
    a, b = b, a + b

The output

[kd@kdlappy book]$ ./fibonacci2.py
1 1 2 3 5 8 13 21 34 55 89