1. We use the value of π in finding perimeter and area of a circle (n is an irrational).
2. To find the length of the diagonal of a square we use √2 which is an irrational one.
3. To find the T.S.A., curved surface area and volumes of solids viz cylinder, sphere, and cone etc. We use K in above case which is an irrational one.
4. For calculation of compound interest, E.M.I. (equal monthly installments) in Banks they use ‘e’ value which is an irrational one.
5. We use these numbers in space and economics related matters thoroughly.