Abstract: A digital system for computing of the values of composite arithmetic expressions, such as ##EQU1## X.sub.IJ WHERE N, K.sub.1, K.sub.2, ....., K.sub.N ARE ARBITRARY INTEGERS, ON NUMBERS X.sub.IJ IN A BINARY SYSTEM FOR APPLICATION IN LARGE COMPUTER SYSTEMS, WITH POSSIBILITY OF A COLLISION-FREE MULTITASK WORK WITH SEVERAL COMPUTERS. The system contains a processing unit for pipeline processing of information to form the partial products for the given multiplicand and multiplier summands. These partial products are the full product summands. It also reduces gradually these summands together with the additional summands of the addition to a smaller number, preferably to two summands. The system contains also a set of registers in which the operands and the intermediate results are stored. The intermediate results in the form of pairs of reduced summands, or of several reduced summands are introduced from the outputs of the processing unit again to the inputs of this same unit, through the set of registers.