why the answer is 5?i need help

Question

var arr=[1,2,3,4,5];
for(var i=0;i<3;i++){
arr[i]*=i;
}
document.write(arr[4]);

Answer 1

Because the loop only changes the value of the first 3 cells here (indexes 0 to 2). The cell at index 4 (ie the 5th cell) is left untouched and is still 5.