A = 2.3 x 10^-3+6 x 10^-4 / 2x10-5
A= (2,3 x 10^-3) ( 1/2 x 10^5) + ( 6x 10^-4 ) ( 1/2 x 10^-5)
A = 2,3 /2 x 10^2 + (6/2 10^-9) = 2^10-1 x 10^2 x ( 2,3 + 3 x 10^-11)
A = 20 x ( 2,3 + 3 x 10^-11) = 46 + 6 x 10^-10
B= 2^(8/3) x 10^4 x 8^(10/9) x 10^-9 = 10^-5 x 2^8/3 x 2^30/9 ( car 8 = 2^3)
B = 10^-5 x 2^24/9 x 2^30/9 = 10^-5 x 2^54/9 = 10^-5 x 2^6
