Math Help - Could someone verify these answers? (Significant Digits)

Hi,

The figures are:

(1.222x10^5)(3.27x10^3) = 3.40x10^8

12.87 - 11.305 + 7.1 = 8.7

3.0/.12345 = 24

The fifth root of -5.113x10^15 = -1386

Thanks!

All good except for the first. 1.222 x 3.27 is not 3.40.

It is correct to "three significant figures".