Either just go ahead and add them up, or use the formula for an arithmetic series.
Sum = 1/2 x number_of_numbers x (first_number + last_number)
= 1/2 x 40 x (1 + 40)
= 20 x 41
= 820.
The sum of the first 40 whole numbers is 780.
20 of them
19,20,21
40 * * * * * The correct answer is 6400.
The sum of the first 20 even numbers... is 110
The sum of the first 40 whole numbers is 780.
The sum of the first 40 odd numbers is 1,600.
The sum of the first 40 even numbers is 1,640.
20 of them
An infinite number.
19,20,21
40 * * * * * The correct answer is 6400.
The sum of the first 20 even numbers... is 110
To find the sum of all prime numbers between 20 and 40, we first list out the prime numbers in that range: 23, 29, 31, 37. Then, we simply add them together: 23 + 29 + 31 + 37 = 120. Therefore, the sum of all prime numbers between 20 and 40 is 120.
1 ,3, 5, 7 ,9......, 77, 79. Sum of first 40 odd numbers is 1600. This is the answer
The sum of the numbers 1 to 39 = 39 x 40 ÷ 2 = 780 The sum of the numbers 1 to 60 = 60 x 61 ÷ 2 = 1830 Therefore the sum of the numbers 40 to 60 = 1830 - 780 = 1050
2+4+6+8+10........+40=420