Posted on May 23, 2013
In the quant section of the GMAT, there are a fair number of formulae to know in order to answer the ensemble of questions that may be asked of you. Most of them are covered in any basic test prep material, but a formula is always just a short hand version of a much longer manual process.
There is an anecdote about a primary school teacher who wanted to keep a misbehaved child busy for a period, so she asked him to sum up all the numbers from 1 to 100. To her dismay, the child answered the question in a matter of seconds, and the answer was correct. The child explained to his teacher that, instead of simply adding 1+2+3…, you could create a pairwise addition that would always yield the same number. If you added 1 to 100, you would get 101. If you added 2 to 99, you would still get 101. If you added 3 to 98, you’d still get 101, and so on. Thus the addition of 100 different numbers could be turned into a multiplication of two simple numbers: 101 x 50. The student in question was mathematical prodigy Carl Friedrich Gauss.