Hard Arithmetic Puzzles

#2137: 4 _ 9 _ 6 _ 7 = 13 hard #2139: 4 _ 9 _ 6 _ 8 = 14 hard #2141: 4 _ 9 _ 6 _ 9 = 15 hard #2144: 4 _ 9 _ 6 _ 6 = 16 hard #2145: 4 _ 9 _ 8 _ 6 = 16 hard #2146: 4 _ 9 _ 8 _ 6 = -8 hard #2147: 4 _ 9 _ 8 _ 4 = 18 hard #2158: 5 _ 2 _ 3 _ 9 = 11 hard #2161: 5 _ 2 _ 3 _ 6 = 20 hard #2168: 5 _ 2 _ 4 _ 8 = 20 hard #2177: 5 _ 2 _ 4 _ 7 = 17 hard #2179: 5 _ 2 _ 4 _ 8 = 18 hard #2180: 5 _ 2 _ 4 _ 9 = 19 hard #2187: 5 _ 2 _ 5 _ 9 = 18 hard #2192: 5 _ 2 _ 6 _ 9 = 15 hard #2193: 5 _ 2 _ 6 _ 2 = 17 hard #2194: 5 _ 2 _ 6 _ 3 = 18 hard #2195: 5 _ 2 _ 6 _ 4 = 19 hard #2197: 5 _ 2 _ 6 _ 5 = 20 hard #2204: 5 _ 2 _ 8 _ 2 = 14 hard #2210: 5 _ 2 _ 8 _ 4 = 20 hard #2211: 5 _ 2 _ 8 _ 2 = 18 hard #2213: 5 _ 2 _ 8 _ 3 = 17 hard #2214: 5 _ 2 _ 8 _ 4 = 16 hard #2215: 5 _ 2 _ 8 _ 5 = 15 hard #2216: 5 _ 2 _ 8 _ 6 = 14 hard #2217: 5 _ 2 _ 8 _ 7 = 13 hard #2219: 5 _ 2 _ 9 _ 3 = 11 hard #2223: 5 _ 2 _ 9 _ 9 = 11 hard #2226: 5 _ 2 _ 9 _ 6 = 15 hard #2228: 5 _ 3 _ 2 _ 8 = 17 hard #2254: 5 _ 3 _ 6 _ 2 = 18 hard #2256: 5 _ 3 _ 6 _ 8 = 20 hard #2265: 5 _ 3 _ 6 _ 7 = 17 hard #2266: 5 _ 3 _ 6 _ 8 = 18 hard #2268: 5 _ 3 _ 6 _ 9 = 19 hard #2270: 5 _ 3 _ 8 _ 2 = 17 hard #2274: 5 _ 3 _ 8 _ 2 = 19 hard #2275: 5 _ 3 _ 8 _ 4 = 17 hard #2276: 5 _ 3 _ 8 _ 8 = 16 hard #2278: 5 _ 3 _ 8 _ 4 = 13 hard #2279: 5 _ 3 _ 8 _ 8 = 14 hard #2280: 5 _ 3 _ 8 _ 6 = 20 hard #2285: 5 _ 3 _ 9 _ 9 = 16 hard #2286: 5 _ 3 _ 9 _ 9 = 14 hard #2288: 5 _ 3 _ 9 _ 1 = 14 hard #2289: 5 _ 3 _ 9 _ 2 = 17 hard #2290: 5 _ 3 _ 9 _ 4 = 19 hard