Success starts with a sharper mind! A generational puzzle book which can be passed down from one generation to next for completion. Solving EXPERT NUMBREX puzzles guarantees to put your brain in top operating condition. EXPERT NUMBREX puzzles challenge your mind two ways. First, translate the result of an addition, subtraction, multiplication or division to decimal from octal, hexadecimal or base32hex number formats. Second, calculate the missing second operand in the arithmetic operation.