Question

Highest poules of 8
cactorial is ginen by ( left[frac{x}{n}right]+left[frac{x}{n^{2}}right]+left[frac{x}{n^{3}}right] )
where ( [cdot] ) refresents greatest integer the series gees on until greatest integer becomes 0 So, highest peren of 7 in 7771 ( =left[frac{77}{8}right]+left[frac{777}{49}right]+left[frac{777}{343}right] )
( +left[frac{777}{2401}right] )
( =111+15+2+0 )
( =128 ) is requiered answer.

# 5. Find the largest power of 7 that can exactly divide 777! (A) 120 (B) 128 (C) 111 (D) 125

Solution