More about nine

Further to my rather awful puzzle poem for my ninth post, here are some more benign thoughts.

My previous boss was rumoured to suddenly ask in interviews, amoungst the usual experience based questions, ‘what is 80% of 90’. Seems a very mean interview question to spring on someone, but is actually easier than it seems as, when it was first mentioned to me, I got the sum the wrong way around and still got the answer right. 90% of 80 and 80% 0f 90 are both 72.

BTW a great way to check if you’ve got your 9 times table right is that when you split the answer up into single digits it will always add up to 9.  For instance in the case above 7+2=9

Providing you keep adding the single digits until you get just one you will always get 9  e.g. 13×9 = 117 and 1+1+7=9 or being more extreme 234×9 = 2106 and 2+1+0+6 = 9


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