To simultaneously perform addition processings for each digit and to shorten operation time by handling a head binary number, i.e., a combination of signals 'o' showing zeros as a scale of notation for at least one of two digits which are adjacent to each other in any digit among those redundant ternary binary numbers of one or plural digits using 2 as a base.

A ternary register which handles ternary signals uses one of three signals {n, o, p} showing the numeric value {-1, 0, 1} respectively as a signal of a single digit and handles a head binary number, i.e., a combination of signals 'o' showing zeros as a scale of notation not as a partial set of redundant ternary binary numbers for at least one of two digits which are adjacent to each other in any digit among those ternary binary numbers of the or plural digits using 2 as a base. As a result, a head binary number which has no redundancy and uniquely corresponds to a binary number with a small rate of non- zero digits can be set at the center of a scale of notation.