Hard Arithmetic Puzzles

#1437: 3 _ 8 _ 3 _ 2 = 15 hard #1440: 3 _ 8 _ 3 _ 6 = 19 hard #1441: 3 _ 8 _ 3 _ 2 = -9 hard #1447: 3 _ 8 _ 4 _ 5 = 13 hard #1448: 3 _ 8 _ 4 _ 6 = 15 hard #1449: 3 _ 8 _ 4 _ 7 = 17 hard #1450: 3 _ 8 _ 4 _ 8 = 19 hard #1453: 3 _ 8 _ 4 _ 6 = -9 hard #1454: 3 _ 8 _ 4 _ 6 = 16 hard #1463: 3 _ 8 _ 4 _ 8 = 14 hard #1465: 3 _ 8 _ 4 _ 9 = 15 hard #1468: 3 _ 8 _ 5 _ 4 = 13 hard #1470: 3 _ 8 _ 5 _ 6 = 20 hard #1471: 3 _ 8 _ 6 _ 3 = 19 hard #1472: 3 _ 8 _ 6 _ 4 = 15 hard #1473: 3 _ 8 _ 6 _ 9 = 15 hard #1474: 3 _ 8 _ 6 _ 4 = -9 hard #1476: 3 _ 8 _ 6 _ 9 = -9 hard #1477: 3 _ 8 _ 6 _ 9 = 16 hard #1483: 3 _ 8 _ 6 _ 4 = 16 hard #1486: 3 _ 8 _ 6 _ 5 = 20 hard #1491: 3 _ 8 _ 6 _ 9 = 13 hard #1493: 3 _ 8 _ 7 _ 4 = 17 hard #1494: 3 _ 8 _ 8 _ 4 = 19 hard #1495: 3 _ 8 _ 8 _ 2 = 20 hard #1496: 3 _ 8 _ 9 _ 6 = 15 hard #1497: 3 _ 8 _ 9 _ 6 = -9 hard #1498: 3 _ 8 _ 9 _ 6 = 16 hard #1505: 3 _ 9 _ 3 _ 5 = 18 hard #1507: 3 _ 9 _ 3 _ 4 = -9 hard #1517: 3 _ 9 _ 3 _ 8 = -7 hard #1519: 3 _ 9 _ 3 _ 9 = -8 hard #1521: 3 _ 9 _ 4 _ 3 = -9 hard #1525: 3 _ 9 _ 5 _ 3 = 18 hard #1526: 3 _ 9 _ 5 _ 9 = 15 hard #1530: 3 _ 9 _ 6 _ 8 = 15 hard #1532: 3 _ 9 _ 6 _ 8 = -9 hard #1547: 3 _ 9 _ 6 _ 8 = 16 hard #1548: 3 _ 9 _ 6 _ 9 = 11 hard #1549: 3 _ 9 _ 6 _ 9 = -7 hard #1550: 3 _ 9 _ 8 _ 6 = 15 hard #1551: 3 _ 9 _ 8 _ 6 = -9 hard #1553: 3 _ 9 _ 8 _ 6 = 16 hard #1573: 4 _ 2 _ 3 _ 8 = 14 hard #1588: 4 _ 2 _ 4 _ 9 = 18 hard #1594: 4 _ 2 _ 4 _ 7 = 15 hard #1597: 4 _ 2 _ 4 _ 9 = 17 hard #1609: 4 _ 2 _ 5 _ 7 = 17 hard