J'arrive pas ! Aidez moi s'il vous plaît :)

a = 13 x10p9x 10p-6  / 2
a = 13 x 10p3 /2
a = 13x 1000 /2
a = 13 000 /2
a = 6500

b = 2 x10p-3x5 / 10p-5
b = 2 x10p-3 -(p-5) x5
b = 2x 10 p2 x5
b = 200x5
b = 1000

c = 15 x10(p-1) )p 3 x 8 / 24x10p-3
c = 15 x 10p-3  x8 x10p3 /24
c =15x8 /24
c =120/24
c =5

d = 10p-2 x 10p 2 / 10p-2
d =  10 / 10p-2
d = 10 x 10p2
d = 10 x100
d =1000


ecriture scientifique de a
6500 x 10p2