Should I always use the "Casting out 9's" trick?
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See the title.
The Daily Challenge with Po-Shen Loh is the best!
aops user = captainnobody -
@professionalbronco Yeah! This trick makes finding remainders when dividing by 9 really fast. It's not too common that a problem will require you to find a number \(\pmod{9}\), but it's definitely very useful for this specific case.
