You can multiply any two digit number with 11 .
It is simple, take any two digit number for example 34 is the number. Now add the both digits of th number. that is 3+4=7.
Now place this addition in between the two digits. so our answer is 374.
So,
54 * 11 = ??

firstly, 5+4= 9

secondly, 594 (answer)

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M.Sc. (telecom).