A dividing circuit and square root extracting circuit using the Newton-Raphson method. The number of places of an initial value of the Newton-Raphson method is decreased, and a part of a multiplier is omitted. Therefore the circuit scale is reduced. A circuit dedicated for the iterated computation circuit for the Newton-Raphson method is mounted, enabling the whole circuits to operate as a pipeline circuit. By cut-off in expanding an iterative operation to a series operation, use of a table, adoption of approximation mode for deriving an initial value, and adoption of redundant expression for computation, higher speed operation and reduction of circuit scale are possible.