bjr
A = 5 x 10¹² - 12 x 10¹¹
= 5 x 10 x 10¹¹ - 12 x10¹¹
= 10¹¹ ( 5 x 10 - 12)
= 10¹¹ (50 - 12)
= 38 x 10¹¹
B = 2 x 10⁻⁸ + 45 x 10⁻¹⁰
= 2 x 10⁻⁸ + 45 x 10⁻² x 10⁻⁸
= 10⁻⁸ (2 + 45 x 10⁻²)
= 10⁻⁸ (2 + 0,45)
= 2,45 x 10⁻⁸
C = 3 x 10⁷ x 11 x (10⁻⁵)²
= 3 x 11 x 10⁷ x 10⁻¹⁰
= 33 x 10⁻³
D = 6 x 10⁷ x (0,4) x 10⁻⁵
= 6 x 0,4 x 10⁷ x 10⁻⁵
= 2,4 x 10²
