Problem
NT-B2-M05-P003 Threes in \(50!\)
#3
★★☆☆☆ Level 2 of 5
Find \(v_3(50!)\).
Add \(\lfloor50/3\rfloor+\lfloor50/9\rfloor+\lfloor50/27\rfloor\).
By Legendre's formula, \(v_3(50!)=16+5+1=22\).
This shows why multiples of \(9\) are counted a second time.