The world of mathematics is full of quirky coincidental neatness. It boggles the mind. Why can the sum of internal angles in polygons be reduced to a single digit of 9? The world seems to be riddled with those patterns of self-similarity? It never seems to amaze me that no matter how many of them you know already there is always someone that knows yet one more.
Well done.
RE: Easy math trick: Another Multiplying number trick.