A calculation speed of division carried out in a computer is increased. Partitioning means partitions a dividend y that is a 32-bit digital datum at every 8 bits from the least significant bit to generate four bit blocks y(1) to y(4). For the respective bit blocks, table reference means finds solutions z(1) to z(4) obtained by dividing, by a divisor x, values expressed by replacing the bits other than the bits in each bit block with 0, while referring to tables (1) to (4) stored in storage means. Addition means adds all the solutions z(1) to z(4) to find the solution z.