PURPOSE: To increase the operating speed of a graphic processor by dividing a bit width necessary for calculation into plural numbers, and operating the calculation by the small bit width.

CONSTITUTION: The graphic processor is equipped with adders 1 - 4, subtracter 5, register 6 for a division number corresponding value, registers 7 and 36, comparators 37 - 39, multiplexers 40 and 41, updown signal generating circuit 42, variable calculating part 50, adding line 50-1, subtracting line 50-2, passing line 50-3, changed amount calculating block 51, one time differentiation line 51-1, two time differentiation line 51-2, and three time differentiation line. Then, the necessary bit width is divided into the plural numbers, and the calculation is operated by the small bit width, so that the propagation time of a carry or a borrow can be shortened. Then, the calculation is proceeded in a pipeline system, and operated in parallel. Thus, the operating time of the graphic processor can be increased.