[рони]

AlexRow,

function calculateProfit(amount, percent, period) {
     let sum = 0;
     for (let i = 0; i < period; i++) {
       let delta = amount * percent / 100;
       sum += delta;
       amount += delta;
     }
     return Math.floor(sum);
   }
   console.log(calculateProfit(1000, 5, 7)); //407
   console.log(calculateProfit(12500, 3, 12)); //5322
   console.log(calculateProfit(0, 3, 1)); //0
   console.log(calculateProfit(100000, 3, 1)); //3000