Abstract: The failure to distinguish between mathematical facts that result either from definition (e. g,,. x = 1) or from logical inference (e.g,, √a. √b = √ab ), and those that require a formal axiomatic proof (e.g,, 1 + 1 = 2) prevents many teachers from offering a simple proof to these so-called “obvious” results. We will look at some of them – how they can easily be derived intuitively without resorting to any formal proof.