1*2*3*...*30 se termina in ? zerouri [tex][\frac{30}{5^1}]=6\;;\;[\frac{30}{5^2}]=1\;;\;[\frac{30}{5^3}]=0 \;;\\
Produsul\;se\;va\;termina\;in\;6+1=7\;zerouri\;[/tex]
1 x2x3...x10 = are 2 zerouri (de la 2x5 si de la inmultirea cu 10) 11x12x13x...x20 = are 2 zerouri (14x15 si inmultirea cu 20) 21x22x23...x30 = are 3 zerouri (24x25=600, adica doua zerouri plus cel de la inmultirea cu 30) 2+2+3 = 7 zerouri
