#### Topic: How to find all?

To find all numbers in decimal numeration with such property: if decimal digits of number to write down upside-down, the same number, only in hexadecimal system turns out. For double-valued numbers: a*10+b=b*16+a ==> a*9=b*15 ==> a = b*5/3 ==> b=3 and =5. Guards that in a statement of the problem it is told "to Find all numbers..." The question: 1) whether there is any upper bound for numbers which satisfy a search criterion; 2) whether there is any numerical regularity for the task decision?