OK * 9 = ALL
ALL * 7 = LETS
LETS * 8 = SOLVE
SOLVE * O = POSER
POSER * 6 = RIDDLE
RIDDLE * S = TEASERS
TEASERS * S = PROBLEMS

POSER * SLY = PROBLEM
My remark: the rows are independent.

Source: Frank Mrazik (on the web)