Multiplication Level 27: 4d x 4d (small). multi-digit window train. 1. Left Edge2131 times 31211. Left EdgeUse the highlighted left edge pair.2131times31212x362 pairs3 pairs4 pairs3 pairs2 pairs1x1Active multiplication train windowraw windowsraw -> 6 | _ | _ | _ | _ | _ | _Use the highlighted left edge pair.2. 2-Pair Window2. 2-Pair WindowAdd both highlighted pairs.2131times31212x362 pairs53 pairs4 pairs3 pairs2 pairs1x1Active multiplication train windowraw windowsraw -> 6 | 5 | _ | _ | _ | _ | _Add both highlighted pairs.3. 3-Pair Window3. 3-Pair WindowAdd all 3 highlighted pairs.2131times31212x362 pairs53 pairs144 pairs3 pairs2 pairs1x1Active multiplication train windowraw windowsraw -> 6 | 5 | 14 | _ | _ | _ | _Add all 3 highlighted pairs. Carry waits for settle.4. 4-Pair Center4. 4-Pair CenterAdd all 4 highlighted pairs.2131times31212x362 pairs53 pairs144 pairs103 pairs2 pairs1x1Active multiplication train windowraw windowsraw -> 6 | 5 | 14 | 10 | _ | _ | _Add all 4 highlighted pairs. Carry waits for settle.5. 3-Pair Right Window5. 3-Pair Right WindowAdd all 3 highlighted pairs.2131times31212x362 pairs53 pairs144 pairs103 pairs82 pairs1x1Active multiplication train windowraw windowsraw -> 6 | 5 | 14 | 10 | 8 | _ | _Add all 3 highlighted pairs.6. 2-Pair Right Window6. 2-Pair Right WindowAdd both highlighted pairs.2131times31212x362 pairs53 pairs144 pairs103 pairs82 pairs51x1Active multiplication train windowraw windowsraw -> 6 | 5 | 14 | 10 | 8 | 5 | _Add both highlighted pairs.7. 1-Pair Right Edge7. 1-Pair Right EdgeUse the highlighted right edge pair.2131times31212x362 pairs53 pairs144 pairs103 pairs82 pairs51x11Active multiplication train windowraw windowsraw -> 6 | 5 | 14 | 10 | 8 | 5 | 1Use the highlighted right edge pair.8. Settle strip8. Settle stripSettle once.Keep ones; carry moves left.raw windows6 | 5 | 14 | 10 | 8 | 5 | 1settled strip6 | 6 | 5 | 0 | 8 | 5 | 1Final multiplication answer6 | 5 | 14 | 10 | 8 | 5 | 1 -> 6650851.