Squares Level 4: 3d center stack (digits 1-9). center-window pre-training. 1. Locate center stackCenter window of 759 times 7591. Locate center stackUse every digit pair whose positions meet in the middle.759times7597x72 pairs3 pairs2 pairs9x9Active multiplication train windowcenter windowUse every digit pair whose positions meet in the middle.2. Add highlighted pairs2. Add highlighted pairs759times7597x72 pairs3 pairs1512 pairs9x9Active multiplication train windowcenter window totalcenter -> 1517 x 9 + 5 x 5 + 9 x 7 = 151.3. Read center total3. Read center totalCenter window answerCenter window = 151.
