18 * 7 = (10 + 8) * 7 = 10 * 7 + 8 * 7 = 70 + 56 = 126
 
17 * 8 = (10 + 7) * 8 = 10 * 8 + 7 * 8 = 80 + 56 = 136
 
19 * 6 = (10 + 9) * 6 = 10 * 6 + 9 * 6 = 60 + 54 = 114
 
106 * 7 − 107 * 6 = (100 + 6) * 7 − (100 + 7) * 6 = (100 * 7 + 6 * 7) − (100 * 6 + 7 * 6) = (700 + 42) − (600 + 42) = 742 − 642 = 100
 
203 * 4 − 204 * 3 = (200 + 3) * 4 − (200 + 4) * 3 = (200 * 4 + 3 * 4) − (200 * 3 + 4 * 3) = (800 + 12) − (600 + 12) = 812 − 612 = 200
 
150 * 6 − 160 * 5 = (100 + 50) * 6 − (100 + 60) * 5 = (100 * 6 + 50 * 6) − (100 * 5 + 60 * 5) = (600 + 300) − (500 + 300) = 900 − 800 = 100
 
180 − 120 * 5 : 6 = 180 − (100 + 20) * 5 : 6 = 180 − (100 * 5 + 20 * 5) : 6 = 180 − (500 + 100) : 6 = 180 − 600 : 6 = 180 − 100 = 80
 
210 − 140 * 5 : 7 = 210 − (100 + 40) * 5 : 7 = 210 − (100 * 5 + 40 * 5) : 7 = 210 − (500 + 200) : 7 = 210 − 700 : 7 = 210 − 100 = 110
 
240 − 160 * 5 : 8 = 240 − (100 * 5 + 60 * 5) : 8 = 240 − (500 + 300) : 8 = 240 − 800 : 8 = 240 − 100 = 140