Hard Arithmetic Puzzles

#846: 2 _ 6 _ 9 _ 9 = 11 hard #851: 2 _ 6 _ 9 _ 5 = 15 hard #852: 2 _ 7 _ 2 _ 2 = 15 hard #853: 2 _ 7 _ 3 _ 6 = 16 hard #856: 2 _ 7 _ 4 _ 8 = 16 hard #857: 2 _ 7 _ 4 _ 4 = 15 hard #859: 2 _ 7 _ 5 _ 5 = 15 hard #862: 2 _ 7 _ 6 _ 6 = 15 hard #865: 2 _ 7 _ 7 _ 7 = 15 hard #867: 2 _ 7 _ 8 _ 2 = 18 hard #868: 2 _ 7 _ 8 _ 8 = 15 hard #871: 2 _ 7 _ 8 _ 8 = 13 hard #872: 2 _ 7 _ 9 _ 3 = 17 hard #873: 2 _ 7 _ 9 _ 9 = 15 hard #874: 2 _ 7 _ 9 _ 3 = 11 hard #876: 2 _ 8 _ 2 _ 3 = 14 hard #878: 2 _ 8 _ 2 _ 2 = 17 hard #879: 2 _ 8 _ 2 _ 2 = 15 hard #882: 2 _ 8 _ 3 _ 2 = 14 hard #885: 2 _ 8 _ 3 _ 6 = 18 hard #887: 2 _ 8 _ 3 _ 3 = 17 hard #888: 2 _ 8 _ 3 _ 3 = 15 hard #893: 2 _ 8 _ 4 _ 7 = 16 hard #894: 2 _ 8 _ 4 _ 8 = 18 hard #895: 2 _ 8 _ 4 _ 9 = 20 hard #898: 2 _ 8 _ 4 _ 4 = 17 hard #899: 2 _ 8 _ 4 _ 4 = 15 hard #902: 2 _ 8 _ 4 _ 5 = 20 hard #915: 2 _ 8 _ 4 _ 9 = -8 hard #918: 2 _ 8 _ 5 _ 5 = 17 hard #919: 2 _ 8 _ 5 _ 5 = 15 hard #920: 2 _ 8 _ 5 _ 4 = 20 hard #923: 2 _ 8 _ 6 _ 9 = 14 hard #924: 2 _ 8 _ 6 _ 2 = 19 hard #925: 2 _ 8 _ 6 _ 6 = 17 hard #926: 2 _ 8 _ 6 _ 3 = 14 hard #927: 2 _ 8 _ 6 _ 6 = 15 hard #929: 2 _ 8 _ 7 _ 4 = 16 hard #930: 2 _ 8 _ 7 _ 7 = 17 hard #931: 2 _ 8 _ 7 _ 7 = 15 hard #932: 2 _ 8 _ 8 _ 8 = 17 hard #934: 2 _ 8 _ 8 _ 8 = 15 hard #935: 2 _ 8 _ 9 _ 4 = 20 hard #936: 2 _ 8 _ 9 _ 6 = 14 hard #937: 2 _ 8 _ 9 _ 3 = 19 hard #938: 2 _ 8 _ 9 _ 9 = 17 hard #939: 2 _ 8 _ 9 _ 9 = 15 hard #943: 2 _ 9 _ 2 _ 2 = 19 hard