5678 + 8765 = 14443 would yield the largest possible sum.
5678 x 5678 = 32239684
The sum is: 600+60+14 = 674
5678*1 = 5678
72% of 5678 = 5678/100 x 72 = 4088.16
5678 + 69022 = 74700
42+5678 = 5720
5678 + 7467 = 13,145
5678 + 2987 = 8,665
sqrt(5678) = 75.35 approx.
7908 + 5678 = 13,586
154.1111