Question

What do you mean by least upper bound

Answer 1

Just Precise Measurements necessary in science, it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. Think of way by which you can estimate the following  (Where an estimate is difficult to ontain, try to get an upper bound on the quantity )
(a) The mass of an Elephant.
(b) The wind speed during the storm.
(c) The number of air molecules in your classroom.