Short version: it is fun.<p>If you do mental math, it makes exercises way more fun if you know more interesting numbers. The 16x18 example is an example.<p>For another example, consider<p><pre><code>  42x49
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When primed by 16x18, one might consider writing it as<p><pre><code>  (45-3)x((45+3)+1) = 45^2-3^2 + 42 = 2025 - 9 + 42 = 2058
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(This works for many pairs of numbers that are relatively close together, only requires one &#x27;large&#x27; multiplication, and that one is simple, as stated in the article)<p>But of course, half-way through, one may realize it is<p><pre><code>  6x7 x 7x7 = 7^4 - 7^3
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Now, 7^3 = 343 (easy to remember in combination with 3^5 = 243), but 7^4 = 2401, for me, doesn&#x27;t pop out (when you say 2401, I know it&#x27;s 7^4, but not vice versa)<p>Meanwhile 49 is close to 50, so we have<p><pre><code>  42x50 - 42 = 2100 - 42 = 2058
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That is faster, but somewhat dull.<p>Meanwhile, as far as we know, the savant calculator just takes the dull road, adding 40x40, 40x(2+9), and 2x9,  doesn&#x27;t get distracted, and produces the right answer in a tenth of the time I take. He has less fun, though, because I take detours to visit tourist attractions.<p>It also can make taxi rides more fun.