レベル１
670×1.8+12×67＝
670 × 1.8 + 12 × 67
= 67 × 10 × 1.8 + 67 × 12
= 67 × 18 + 67 × 12
= 67 × (18 + 12)
= 67 × 30
= 2010
筑波大附属
720 × 1.4 + 28 × 72
= 72 × 10 × 1.4 + 28 × 72
= 72 × 14 + 72 × 28
= 72 × (14 + 28)
= 72 × 42
= 3024
130 × 2.4 + 76 × 13
= 13 × 10 × 2.4 + 76 × 13
= 13 × 24 + 13 × 76
= 13 × (24 + 76)
= 13 × 100
= 1300
85 × 65 + 850 × 3.5
= 85 × 65 + 85 × 10 × 3.5
= 85 × 65 + 85 × 35
= 85 × (65 + 35)
= 85 × 100
= 8500
250 × 3.2 + 68 × 25
= 25 × 10 × 3.2 + 68 × 25
= 25 × 32 + 25 × 68
= 25 × (32 + 68)
= 25 × 100
= 2500
レベル2
740 × 2.6 + 74 × 74
= 74 × 10 × 2.6 + 74 × 74
= 74 × 26 + 74 × 74
= 74 × (26 + 74)
= 74 × 100
= 7400
350 × 4.8 – 35 × 38
= 35 × 10 × 4.8 – 35 × 38
= 35 × 48 – 35 × 38
= 35 × (48 – 38)
= 35 × 10
= 350
125 × 0.7 + 12.5 × 93
= 12.5 × 10 × 0.7 + 12.5 × 93
= 12.5 × 7 + 12.5 × 93
= 12.5 × (7 + 93)
= 12.5 × 100
= 1250
レベル３
4 × 4 × 5.14 – 51.4 × 0.75 + 0.257 × 30
= 16 × 5.14 – 5.14 × 10 × 0.75 + 2.57 × 3
= 16 × 5.14 – 5.14 × 7.5 + 5.14 × 0.5 × 3
= 16 × 5.14 – 7.5 × 5.14 + 1.5 × 5.14
= 5.14 × (16 – 7.5 + 1.5)
= 5.14 × (10)
= 51.4