Addition of large numbers

Algorithm is summarized ： Add large numbers

We will inevitably encounter large numbers in the process of calculation , And a variable cannot be stored , So we need to use the linear table to calculate .
We can pass an example
1!+2!+3!+4!+…50!

int n,a[1000]={
    0},b[1000]={
    0}; // Initialize the array to zero 
    scanf("%d",&n);
    a[0]=b[0]=1;          // Take the first element as 1 Convenient for later multiplication 
    for(int i=2;i<=n;i++){
    
    for(int j=0;j<100;j++)
           a[j]*=i;   
                            // stay a Calculate the factorial of each number in this array 
    for(int j=0;j<100;j++)
        if(a[j]>9){
    
           a[j+1]+=a[j]/10;
           a[j]%=10;
        }

 This part is the result of calculating the factorial number of each part 

        for(int j=0;j<100;j++){
    
            b[j]+=a[j];
            if(b[j]>9){
    
            b[j+1]+=b[j]/10;
            b[j]%=10;
            }
        }

 This section is to calculate the sum of each factorial result 

Therefore, through the array, you can calculate large numbers so that there will be no data overflow in a single variable .