
@Xx17965797N When I was in high school, I noticed that if you subtract any 2-digit number from its reverse, the answer is always the multiple of 9 times the difference between the two numbers:
84-48=36; 8-4=4; 9x4=36
72-27=45; 7-2=5; 9x5=45
31-13=18; 3-1=2; 9x2=18
52-25=27; 5-2=3; 9x3=27
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