Implementations of this specification provide a method and apparatus for computer data processing for large number operations. An example method performed by a computing device includes splitting a multiplier and a multiplicand into respective four 64-bit numbers from most significant bits to least significant bits; reading the split multipliers and the split multiplicands into a register; and obtaining a multiplication processing result for the multiplier and the multiplicand by performing operations including: classifying the split multipliers and the split multiplicands into groups of data pairs, calculating multiplication results of the groups of data pairs one by one, performing accumulation on multiplication results of data pairs in each group, and storing an accumulation result corresponding to the data pairs in memory as the multiplication processing result for the multiplier and the multiplicand.