1. 
console.log("--------------1---------------")
var Num1;
var Num2;

if (Num1 > Num2){
  console.log(Num1 + " is the greatest")
} else if (Num2 > Num1){
  console.log(Num2 + " is the greatest")
} else { 
  console.log("The numbers are the same")
}

2. 
console.log("--------------2---------------")
var Num;
var i;

i=0;
Num= 10;

while(i<=Num){
  console.log(i);
  i++;
}

3. 
console.log("--------------3---------------")

var number_1;
var number_2;
var gdc;

number_1 = 5;
number_2 = 3;

if (number_1<number_2){
  for(var x=1; x<=number_1; x++){
    if (number_1%x==0 && number_2%x==0){
      gdc=x
    }
  }
}else if (number_1>number_2){
  for(var x=1; x<=number_2; x=x+1){
    if (number_1%x==0 && number_2%x==0){
      gdc=x
    }
  }
}else{
  gdc= number_1
}

console.log(gdc + " is the greatest common divisor between " + number_1 + " and " + number_2)



4.
console.log("--------------4---------------")
var num_1;
var num_2;
var num_3;

num_1 = 10;
num_2 = 20;
num_3 = 5;

if(num_1>num_2 && num_1>num_3){
  console.log(num_1+ " is the greatest");
} else if (num_2>num_1 && num_2>num_3){
  console.log(num_2 +" is the greatest");
} else if (num_3 >num_2 && num_3>num_1){
  console.log(num_3 +" is the greatest")
} else {
  console.log("there are at least two numbers that are the greatest")
}



5.
console.log("--------------5---------------")
for (let yr=2021; yr<= 2050; yr++){
  if (yr%4==0){
    console.log(yr + " is a leap year");
  }else if(yr%400==0 && yr%100!=0){
    console.log(yr + " is a leap year");
  }
}