CUET Preparation Today
CUET
Section B2
Numbers, Quantification and Numerical Applications
If $\phi (n)$ represents Euler quotient function, then what is the value of $\phi (77)$ ?
80
100
60
70
The correct answer is option (3) : 60
77 = 7 × 11 (both are prime numbers)
Using Euler’s totient formula: ϕ(n) = n(1 − 1/p)(1 − 1/q)
ϕ(77) = 77(1 − 1/7)(1 − 1/11) = 77 × (6/7) × (10/11) = 66 × (10/11) = 60