1,22×10^6+3.79×10^6=122000+379000=501000;
4,2×10^-3 -2,5×10^-3 = 4,2×0.001-2,5×0.001=0.0042-0.0025=0.0017;
9,5×10^7-3,9×10^7=9,5×10000000-3.9×10000000=95000000-39000000=56000000;
6,7×10^-6 - 4,22×10^-6 = 6,7×0,000001-4,22×0.000001=0.0000067-0.00000422=0.00000248.