680 + 440 = 1120
439 + 71 = 510
520.
439 + 71 = 439 + 1 + 70 = 440 + 70 = 510. Who needs a ball park estimate when the exact answer is just as easy to find?
nothing at all
234 + 678 = 912
789 + 678 = 1467
678 + 75 = 753
439 + 746 = 1185
567 + 678 = 1,245
87794 + 39357 + 180 + 439 = 127,770
9 plus 2 plus 2 plus 45-678 is equal to -620.
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