bjr
Ecrire en base 10 les nombres a, b, c, d, e et f écrits en base 2.
a = 1 ; b = 10 ; c = 100 ; d = 1010 ; f = 1101011
observe
en base 10 :
3257 = 3000 + 200 + 50 + 7
= 3 x 10³ + 2 x 10² + 5 x 10¹ + 7 x 10⁰
en base 2 :
101101 = 1 x 2⁵ + 0 x 2⁴ + 1 x 2³ + 1 x 2² + 0 x 2¹ + 1 x 2⁰
a₂ = 1 -> a₁₀ = 1 x 2⁰ = 1 (2⁰ = 1)
b₂ = 10 -> b₁₀ = 1 x 2¹ + 0 x 2⁰ = 2
c₂ = 100 -> c₁₀ = 1 x 2² + 0 x 2¹ + 0 x 2⁰ = 4
d₂ = 1010 -> d₁₀ = 1 x 2³ + 0 x 2² + 1 x 2¹ + 0 x 2⁰ = 8 + 2 = 10
f₂ = 1101011 ->
f₁₀ = 1 x 2⁶ + 1 x 2⁵ + 0 x 2⁴ + 1 x 2³ + 0 x 2² + 1 x 2¹ + 1 x 2⁰
= 64 + 32 + 0 + 8 + 0 + 2 + 1 = 107
