210
439 + 71 = 510
439 + 71 = 439 + 1 + 70 = 440 + 70 = 510. Who needs a ball park estimate when the exact answer is just as easy to find?
520.
nothing at all
sava
680 + 440 = 1120
5200 and 70
It is 71 + 30 = 101.
You can see clearly that the actual answer is 722 but if you have to, estimate 790 - 70 = 720
1 and 439. 439 is prime.
The positive integer factors of 439 are: 1, 439
Only 1 and 439 because 439 is a prime number.