This can be found 2 ways: a) the long way 1+3+5+7+9+11+13+15+17+19= 100 or b) the twentieth odd number is 19. 1 +19 = 20, 3+ 17 = 20, etc. there are 5 pairs of this meaning five pairs of numbers that add up to 20. 5x20 = 100.
1,3,5,7,9,11,13
64
The sum of the first 100 odd numbers (1 through 199) is 10000 (ten thou)
The sum of the first 300 odd numbers is 90,000
The sum of the first 40 odd numbers is 1,600.
64
the answer is 49.
1,3,5,7,9,11,13
The sum of the first 100 odd numbers (1 through 199) is 10000 (ten thou)
The sum of the first 300 odd numbers is 90,000
The sum of the first 1,000 odd numbers is 1,000,000.
The sum of the first 13 odd numbers is 169.
The sum of the first nine odd numbers is 81.
The sum of the first 153 odd numbers is 23,409.
The sum of the first 40 odd numbers is 1,600.
The sum of the first 50 odd numbers is 2,500.
The sum of the first 600 odd numbers is 360,000.