index.js

import multiply from './multiply';
import sum from './sum';
const totalMultiply = multiply(5, 3);
const totalSum = sum(5, 3);
console.log(`Product of 5 and 3 = ${totalMultiply}`);
console.log(`Sum of 5 and 3 = ${totalSum}`);

multiply.js

import sum from './sum';
const multiply = (a, b) => {
    let total = 0;
    for(let i=0;i<b;i++) {
        total = sum(a, total);
    }
    return total;
};
export default multiply;

sum.js

const sum = (a, b) => a + b;
export default sum;