Four matrices M1, M2, M3 and M4 are dimensions p × q, q × r, r × s and s × t respectively can be multiplied in several ways with different number of total scalar multiplications. For example When multiplied as (( ) ( )) 1 2 3 4 M ×M × M ×M the total number of scalar multiplications is pqr+rst+prt. When multiplied as ((( ) ) ) 1 2 3 4 M ×M ×M ×M , the total number of scalar multiplications is pqr+prs+pst.
If p=10, q=100, r=20, s=5 and t=80, then the minimum number of scalar
multiplications needed is??