Bonjour,
a. (10^9)^4 = 10^36
b. 10^-4 / 10^9 = 10^-13
c. 10^12 x 10^-8 x 10^5 = 10^9
d. 10^-6 / 10^6 = 10^-12
e (10^41 x 10^7)/10^-39 = 10^87
f. 10^-9 x 10^12 = 10^3
g. 10^-7/10^8 = 10^-15
h. (10^-3)^-6 = 10^18
i. 10^10/10^-5 = 10^15
j. 10^21/ (10^-4 x 10^-18) = 10^43