Without multiplying out, the value of $97^2-3^2$ is:

Use the difference of two squares: $a^2-b^2=(a-b)(a+b)$. Here $97^2-3^2=(97-3)(97+3)=94\times 100=9400$. Checking the long way, $97^2=9409$ and 9409 − 9 = 9400. Stopping at 94 uses only the first bracket.