Question

You have a weighting machine and you use only one time. Now,you have 10 pencil ✏ box in same size. 9 pencil ✏ box has 10 pencils of 10gm. Now,one box has 10 pencils of 9gm. And you answer me that which pencil box has 90gm?

Answer 1

what a simple question the box containing 10 pencils of 9 grams will weigh 90 grams