PERFECT GIFT FOR NUMBER PUZZLE LOVERS! Success starts with a sharper mind! Solving NUMBREX puzzles guarantees to put your brain in top operating condition. NUMBREX puzzles challenge your mind two ways. First translate the result of an addition, subtraction, multiplication or division to decimal from binary, hexadecimal or roman numeral number formats. Second calculate the missing second operand in the arithmetic operation. NUMBREX & SOLUTION 2952. 53 - ____ = 10000 2953. 7 * ____ = LXXXIV 2954. 12