22424+2626252515717=2,626×10¹²

No. The exact sum is:

22424 + 2626252515717 = 2626252538141

In scientific notation: 2.626252538141 × 10^12.

This is not equal to 2.626 × 10^12. The difference is 252,538,141 (about 0.0096% of 2.626×10^12). If you round to three significant figures, you’d get 2.63×10^12.