Tuesday, 14 October 2025

Exercise (1.1).5

Compute 𝜏 (n) (tau function) for the following n values:

(a) 10

(b) 100

(c) 120

(d) 101


(a) The factors of 10 are $\{1, 2, 5, 10\}$.

Therefore $\tau (10) = 4$.


(b) The factors of 100 are $\{1, 2, 4, 5, 10, 20, 25, 50, 100\}$.

Therefore $\tau (100) = 9$.


(c) The factors of 120 are $\{1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40, 60, 120\}$.

Therefore $\tau (120) = 16$.


(d) The factors of 101 are $\{1, 101\}$.

Therefore $\tau (101) = 2$.