How to solve
(2.31*10^-6)+(3.41*10^3)

Remove the unnecessary brackets
2.31 x 10^-6+3.41 x 10^3

Convert the decimal to a fraction
231/100 x 10^-6 + 3.41 x 10^3

Multiply
231/100 x 1/10^6 + 3.41 x 1000

Combine
231/100 x 1/10^6 + 3410

Calculate
231/(10^2 x 10^6) + 3410

231/10^8 + 3410

Hope it helped :)