wikipedia - 17 Jul 2022
This sequence (4, 13, 28, 27, 18) is called the acyclic or linear convolution of the two original sequences (1,2,3) and (4,5,6). Once we have the acyclic convolution of two sequences, computing the product of the original numbers is easy: we just perform the carrying (for example, in the rightmost column, we keep the 8 and add the 1 to the column containing 27). In the example this yields the correct product 56088.