As it is for loop and The loop is started from the i=0 , after that check the condition 0<=20 condition is true .The control moves to the body of loop and it print Looping again! on the console window .After that it increment the value of i=i+1 .
Now i=1 1<=20 condition is true .The control moves to the body of loop and it print Looping again! on the console window .After that it increment the value of i=i+1 .
i=2 2<=20 condition is true .The control moves to the body of loop and it print Looping again! on the console window .After that it increment the value of i=i+1 .
............soon
This process is executed again and again but when the value i=21 the loop condition is false .The loop is terminated .
As the loop is starts from the i=0 and executed less then equal to 20 therefore 21 times the loop is executed .
