why this code is producing is output in terms of exponential for large values

Question

Why the code(A) is producing is output in terms of exponential for large values.

for eg:-input(in)=1400000 output:-1.2375e+006(without using variable k).

An integer "in" denoting income in rupees is given. Find net income. The net income is calculated by subtracting the total tax (also called tax reduction) from the total income.

long long int in;
        cin>>in;
        long long int a,b,c,d,e;
        a=(250000)*0.05;
        b=(250000)*0.10+a;
        c=(250000)*0.15+b;
        d=(250000)*0.20+c;
        e=(250000)*0.25+d;

code without using variable (long long)k

code(A)

        cout<<1LL*in<<endl;
        else if(in<=500000)
        cout<<1LL*(in-((in-250000)*0.05))<<endl;
        else if(in<=750000)
        cout<<1LL*(in-a-((in-500000)*0.10))<<endl;
        else if(in<=1000000)
        cout<<1LL*(in-b-((in-750000)*0.15))<<endl;
        else if(in<=1250000)
        cout<<1LL*(in-c-((in-1000000)*0.20))<<endl;
        else if(in<=1500000)
        cout<<1LL*(in-d-((in-1250000)*0.25))<<endl;
        else
        cout<<1LL*(in-e-((in-1500000)*0.30))<<endl;

whereas input(in)=1400000 output:-1237500(using variable (long long)k)

code using (long long)k

code(B)

        long long int k;
        if(in<=250000)
          k=in;
        else if(in<=500000)
          k=(in-((in-250000)*0.05));   
        else if(in<=750000)
          k=(in-a-((in-500000)*0.10));
        else if(in<=1000000)
          k=(in-b-((in-750000)*0.15));
        else if(in<=1250000)
          k=(in-c-((in-1000000)*0.20));
        else if(in<=1500000)
          k=(in-d-((in-1250000)*0.25));
        else 
          k=(in-e-((in-1500000)*0.30));
        cout<<k<<endl;