万以内四位数的加减法口算：4492 - 3409 = 4814 + 4678 = 4174 - 1986 = 1242 - 1014 = 7648 + 1606 = 8314 + 1415 =2523 + 5841 = 3536 - 2768 = 5984 + 1393 = 9379 - 3724 = 1297 + 6439 = 8125 - 2304 =2396 - 1738 = 5590 + 2856 = 5126 + 2455 = 4492 - 3409 = 4814 + 4678 = 4174 - 1986 = 1242 - 1014 = 7648 + 1606 = 8314 + 1415 = 2523 + 5841 = 3536 - 2768 = 5984 + 1393 = 9379 - 3724 = 1297 + 6439 = 8125 - 2304 = 2396 - 1738 = 5590 + 2856 = 5126 + 2455 = 4492 - 3409 = 4814 + 4678 = 4174 - 1986 = 50001234 =
