Factorial of large number in ruby(programming language)....
#Author"shivamzaz"@imsec(2cs)(2ndyr)
#Based on simple maths concept(carry based)
#Large value factorial in ruby...
#Session"2015"
def factorial(n);
    a=[]        #intialize array
    a[0]=1      #let fist value of array is 1 as usual like factorial simple defn concept
    a_size=1     
    for x in 2..n;      
        a_size=mult(x,a,a_size)    #function call
    end
    g=a.size-1                     #display the result in reverse wise.....due to carry maintenance
    while(g>=0);
        print a[g]
        g-=1
    end
end
def mult(x,a,a_size);                        
    cry=0
    for i in 0..a_size-1;
        pro=x*a[i]+cry
        cry=pro/10
        a[i]=pro%10
    end
    while(cry>0);
        a[a_size]=cry%10
        cry=cry/10
        a_size+=1
    end
    return a_size
end
factorial(gets().to_i)    #fucnction call
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that's all...

                                <<<<<<<Happy Coding>>>>>.