80 − 16 * 5 = 80 − (10 + 6) * 5 = 80 − (10 * 5 + 6 * 5) = 80 − (50 + 30) = 80 − 80 = 0
 
70 + 2 * 12 = 70 + 2 * (10 + 2) = 70 + (2 * 10 + 2 * 2) = 70 + (20 + 4) = 70 + 24 = 94
 
90 : (6 * 15) = 90 : (6 * (10 + 5)) = 90 : (6 * 10 + 6 * 5) = 90 : (60 + 30) = 90 : 90 = 1
 
68 : (72 : 18) = 68 : 4 = (40 + 28) : 4 = 40 : 4 + 28 : 4 = 10 + 7 = 17
 
78 : (13 − 7) * 0 = 78 : 6 * 0 = (60 + 18) : 6 * 0 = (60 : 6 + 18 : 6) * 0 = (10 + 3) * 0 = 13 * 0 = 0
 
64 : (39 − 7) * 1 = 64 : 32 * 1 = 2 * 1 = 2