If ‘n’ is an integer between 0 and 21, then the minimum value of n! (21 – n)! is

n!(21−n)!=21!n!(21−n)!21!=21!1 21Cn=21! 21CnFor minimum value,  21Cn is maximum.Maximum value of  21Cn=21C21−1=21C10∴  Minimum value =21! 21C10=21!21!×10!11!=10!11!