adde new code lesson

src/index.ts

@@ -2,3 +2,29 @@
 
 //lesson 1.5 SUM OF NUMBERS
 
+function CalculateRectangleArea(sideA: number, sideB: number) : number {
+  return sideA * sideB;
+}
+
+//Virtual console
+let chisloOne: string = '2';
+let chisloTwo: string = 'A';
+
+//Solution
+let sideA = Number.parseInt(chisloOne, 10);
+let sideB = Number.parseInt(chisloTwo, 10);
+
+// && - AND
+// || - OR
+// !
+if (Number.isNaN(sideA) || sideA <= 0 ){
+  console.log(`Your first value is invalid: ${sideA}`)
+}
+if (Number.isNaN(sideB) || sideB <= 0){
+  console.log(`Your second value is invalid: ${sideB}`)
+}
+
+else{
+  console.log(`Area of rectangle is: ${CalculateRectangleArea(sideA, sideB)}`);
+}
+