Bonjour
10^n x 10^m = 10^(n+m)
10^n/10^m = 10^(n-m)
(10^n)^m = 10^(nxm)
C = (10^(-2) x 10^(-7))/(10^6)
C = 10^(-2-7-6)
C = 10^(-15)
D = (10^(-4) x 10^9)/(10^5 x 10^(-7))
D = 10^(-4+9-5+7)
D = 10^(-9+16)
D = 10^7
E = [(10^4)^(-2) x 10]/10^(-3)
E = 10^(4x(-2)) x 10^(1+3)
E = 10^(-8+4)
E = 10^(-4)