21 乘法 40 等于多少？

21 × 39 = 819 21 × 41 = 861 21 × 38 = 798 21 × 42 = 882 21 × 37 = 777 21 × 43 = 903 21 × 44 = 924 21 × 36 = 756 20 × 40 = 800 22 × 40 = 880 19 × 40 = 760 23 × 40 = 920 24 × 40 = 960 18 × 40 = 720 25 × 40 = 1000 17 × 40 = 680 10 × 84 = 840 12 × 70 = 840 14 × 60 = 840 15 × 56 = 840 20 × 42 = 840 24 × 35 = 840 31 × 55 = 1705 90 × 45 = 4050 60 × 85 = 5100 47 × 31 = 1457 89 × 23 = 2047 6 × 70 = 420 44 × 45 = 1980 40 × 48 = 1920