1) 17 6 * 7 3 + 1 - * 12 + >> 17 * 6 * (7 + 3 - 1) + 12 = 930
2) 12 10 + 3 8 * + 7 + 2 * >> (12 + 10 + 3 * 8 + 7) * 2 = 106
3) 11 8 7 5 11 + - + - >> 11 - (8 + 7 - (5 + 11)) = 12
4) 15 8 3 1 2 - - - - >> 15 - 8 - 3 - 1 - 2 = 1