The idea here is to use the formula for the sum of an arithmetic series. In this case, the starting number is of course 1; the interval is 2.
The sum of the first 60 consecutive odd numbers is 3,600.
23+21+19+17=80
The sum of the first 600 odd numbers is 360,000.
The sum of the first 15 odd numbers is 225.
The sum of the first 8,000 odd numbers 64,000,000.
The sum of the first 50 odd numbers is 2,500.
The sum of the first 1,000 odd numbers is 1,000,000.
The sum of the first 100 odd numbers is 10,000.
The sum of the first 300 odd numbers is 90,000
The sum of the first 40 odd numbers is 1,600.
The sum of the first 13 odd numbers is 169.
The sum of the first 153 odd numbers is 23,409.