If $\phi (n)$ represents Euler quotient function, then what is the value of $\phi (420)$ ?
Answer & explanation
Correct answer: option 3
The correct answer is option (3) : 96
$\phi (420) = \phi (2^3×3×5×7)$
$=\phi (2^2) ×\phi (3) × \phi (5)×\phi (7)$
$= (2^2-2^1) ×(3-1)×(5-1)×(7-1)$
$= 2×2×4×6 = 96 $