Calculate Balance Instalment in C

Problem

Write a C program to calculate a balance installment that is to be paid after every month for a particular loan amount (with interest).

Solution

Following is the formula to calculate interest when the loan amount is given −

i=loanamt * ((interest/100)/12);

Following calculation gives amount with interest −

i=i+loanamt;
firstmon=i-monthlypayment; //first month payment with interest
i=firstmon * ((interest/100)/12);

Program

 Live Demo

#include<stdio.h>
int main(){
   float loanamt,interest,monthlypayment;
   float i,firstmon,secondmon;
   printf("enter the loan amount:");
   scanf("%f",&loanamt);
   printf("interest rate:");
   scanf("%f",&interest);
   printf("monthly payment:");
   scanf("%f",&monthlypayment);
   //interest calculation//
   i=loanamt * ((interest/100)/12);
   //amount with interest
   i=i+loanamt;
   firstmon=i-monthlypayment; //first month payment with interest
   i=firstmon * ((interest/100)/12);
   i=i+firstmon;
   secondmon=i-monthlypayment; //second month payment with interest
   printf("remaining amount need to pay after 1st installment:%.2f
",firstmon);
   printf("remaining amount need to pay after 2nd installment:%.2f
",secondmon);
   return 0;
}

Output

enter the loan amount:45000
interest rate:7
monthly payment:1000
remaining amount need to pay after 1st installment:44262.50
remaining amount need to pay after 2nd installment:43520.70