• Execution time of an algorithm depends on numbers of instruction executed.
• Consider the following algorithm fragment: 

for i = 1 to n do

• The for loop executed n+1 times for i values 1,2,....... n, n+1. Each instruction in the body of the loop is executed once for each value of i = 1,2,......, n. So number of steps executed is 2n+1.
• Consider another algorithm fragment:

• From prevoius example, number of instruction executed in the inner loop is which is the body of outer       loop.
• Total number of instruction executed is