1. If two digits number and a number obtained by reversing its digits are added then it will be divisible by 11.Ex-12+21=33,it is divisible by 11.
45+54=99, it is divisible by 11.
2. If two digits number and a number obtained by reversing its digits are subtracted then it will be divisible by 9.
Ex-65-56=9, it is divisible by 9.
93-39=54, it is divisible by 9.
3. If two digits number and its sum of digits are subtracted then it will be divisible by 9.
Ex-13-(1+3)=9, it is divisible by 9.
29-(2+9)=18, it is divisible by 9.
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