Sum of first fifteen natural numbers is 1+2+3+4+5+6+7+8+9+10+11+12+13+14+15=120

Sum of First 15 Natural Numbers

The sum of the first 15 natural numbers refers to the addition of the numbers starting from 1 up to 15. Natural numbers are positive integers (whole numbers) starting from 1, so the sum of the first 15 natural numbers can be calculated using a simple formula.

Formula:

The sum of the first n natural numbers can be calculated using the formula:

Sum = (n/2)(first number + last number)

where n represents the number of terms and the first number is 1.

Calculation:

In this case, we need to find the sum of the first 15 natural numbers, so n = 15.

Using the formula, the sum can be calculated as:

Sum = (15/2)(1 + 15)
= (15/2)(16)
= 15 * 8
= 120

Therefore, the sum of the first 15 natural numbers is 120, which corresponds to option 'D'.

Explanation:

To understand the calculation, let's break it down step by step:

1. First, we substitute the value of n (number of terms) into the formula, which is 15 in this case.
2. Next, we determine the first number, which is always 1 for the sum of natural numbers.
3. The last number can be obtained by taking the value of n, which is 15 in this case.
4. Then, we substitute the values into the formula and simplify the expression.
5. Finally, we calculate the result by multiplying the two values obtained in the previous step.

The sum of the first 15 natural numbers is 120, as calculated above. This means that if we add the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 together, the sum would be 120.