Exercice 2

Sans calculatrice donner l' écriture scientifique (c'est-à-dire sous la forme \(a × 10^n\) avec 1 \(\leq a < 10\) et \(n \in \mathbb{Z} \)) de chaque nombre :

Question

\(382000\)

Solution

On a \( 382000 = 3, 82 × 10^5 \)

Question

\(400 × 10^{−6}\)

Solution

\(400 × 10^{−6} = 4 × 10^{−4}\)

Question

\(0, 0000455 × 10^4 \)

Solution

\(0, 0000455 × 10^4 = 4, 55 × 10^{−1}\)

Question

\(\cfrac{15 × 10^{-4}}{10^{-2}}\)

Solution

\(\cfrac{15 × 10^{-4}}{10^{-2}} = 1, 5 × 10^{−1}\)

Question

\( 0, 03 × 10^{−7} × 0, 5 × 10^2 \)

Solution

\(0, 03 × 10^{−7} × 0, 5 × 10^2 = 1, 5 × 10^{−7}\)

Question

\(\cfrac{9 × 10^{−4} × 4, 5 × 10^{−4}}{ 3 × 10^{−6} × 5}\)

Solution

\(\cfrac{9 × 10^{−4} × 4, 5 × 10^{−4}}{ 3 × 10^{−6} × 5}= 2, 7 × 10^{−2}\)

Question

\(\cfrac{25 × 10^{6} × 8 × 10^{2}}{ 2 × 10^{2} }\)

Solution

\(\cfrac{25 × 10^{6} × 8 × 10^{2}}{ 2 × 10^{2} }= 10^{8}\)