It is so very simple and quick to get the answer, especially since, if you need it, you can use the calculator that comes with your computer. But since you are obviously not able to do so, the answer is 690.
345 + 890 + 549 = 1784
345 + 435 = 780
345 + 67797808 = 67798153
55555555 + 345 = 55555900
200 + 345 = 545
345 + 890 = 1235
325 + 345 = 670
2 + 345 = 347
345 + 253 = 598
1 + 55 + 345 + 87 + 98 = 586
1 billion and 345
345 + 69 = 414