Medium Arithmetic Puzzles

#843: 2 _ 6 _ 9 _ 6 = -2 medium #850: 2 _ 6 _ 9 _ 4 = 12 medium #854: 2 _ 7 _ 3 _ 3 = 13 medium #858: 2 _ 7 _ 4 _ 4 = 13 medium #860: 2 _ 7 _ 5 _ 5 = 13 medium #863: 2 _ 7 _ 6 _ 2 = 11 medium #864: 2 _ 7 _ 6 _ 6 = 13 medium #866: 2 _ 7 _ 7 _ 7 = 13 medium #869: 2 _ 7 _ 8 _ 2 = 10 medium #870: 2 _ 7 _ 8 _ 4 = 12 medium #883: 2 _ 8 _ 3 _ 4 = 8 medium #886: 2 _ 8 _ 3 _ 4 = -4 medium #889: 2 _ 8 _ 3 _ 4 = 12 medium #891: 2 _ 8 _ 4 _ 3 = 8 medium #892: 2 _ 8 _ 4 _ 5 = 12 medium #896: 2 _ 8 _ 4 _ 3 = -4 medium #897: 2 _ 8 _ 4 _ 5 = -8 medium #900: 2 _ 8 _ 4 _ 3 = 12 medium #909: 2 _ 8 _ 4 _ 6 = -5 medium #910: 2 _ 8 _ 4 _ 7 = 8 medium #911: 2 _ 8 _ 4 _ 7 = -6 medium #912: 2 _ 8 _ 4 _ 8 = 9 medium #913: 2 _ 8 _ 4 _ 8 = -7 medium #914: 2 _ 8 _ 4 _ 9 = 10 medium #916: 2 _ 8 _ 5 _ 4 = 12 medium #917: 2 _ 8 _ 5 _ 4 = -8 medium #933: 2 _ 8 _ 8 _ 2 = 12 medium #940: 2 _ 8 _ 9 _ 4 = 9 medium #941: 2 _ 9 _ 2 _ 3 = 8 medium #942: 2 _ 9 _ 2 _ 3 = -4 medium #948: 2 _ 9 _ 3 _ 2 = -4 medium #959: 2 _ 9 _ 3 _ 9 = -3 medium #963: 2 _ 9 _ 4 _ 6 = -4 medium #965: 2 _ 9 _ 4 _ 6 = 12 medium #966: 2 _ 9 _ 4 _ 8 = 9 medium #972: 2 _ 9 _ 6 _ 4 = -4 medium #977: 2 _ 9 _ 6 _ 3 = 6 medium #979: 2 _ 9 _ 6 _ 4 = 7 medium #981: 2 _ 9 _ 6 _ 4 = 12 medium #982: 2 _ 9 _ 6 _ 5 = 8 medium #983: 2 _ 9 _ 6 _ 5 = -2 medium #985: 2 _ 9 _ 6 _ 6 = 9 medium #986: 2 _ 9 _ 6 _ 6 = -3 medium #987: 2 _ 9 _ 6 _ 7 = -4 medium #989: 2 _ 9 _ 6 _ 9 = -6 medium #1005: 3 _ 1 _ 3 _ 9 = 6 medium #1012: 3 _ 2 _ 3 _ 9 = -3 medium #1015: 3 _ 2 _ 3 _ 7 = 14 medium