1)49 * 362 + 51 * 362 = ( 49 + 51 ) * 362 = 100 * 362 = 36200
2)658 * 29 - 657 * 29 = ( 658 - 657 ) * 29 = 29
3)394 * 268 + 394 * 232 = ( 268 + 232 ) * 394 = 500 * 394 = 197000
4)64 * 258 - 64 * 39 - 64 * 19 = ( 258 - 39 - 19 ) * 64 = 200 * 64 = 12800