 Hello all and welcome to the session. Today, the question is, find the exterior angle of a regular polygon of 18 sides. Now, before starting the solution of this question, we should know a formula to find out the exterior angle of a polygon. And that is, each exterior angle of regular polygon n sides is equal to 4 mm right angles. Now, this formula will work out as a key idea for solving out this question. And now, we will start with the solution. Given number of sides of the regular polygon which is equal to n is equal to 18. Now, according to the formula which is given in the key idea, each exterior angle of the regular polygon of 18 sides is equal to 4 by n, where n is equal to 18, 4 by 18 into right angles, which is equal to 4 by 18 into 90 degrees. Now, 9 into 2 is 18 and 9 into 10 is 90 and 2 into 2 is 4. So, this will be equal to 20 degrees. Hence, exterior angle of a regular polygon of 18 sides is equal to 20 degrees. So, this is the solution of the given question. And that's all for this session. Hope you all have enjoyed the session.