Legend has it that the great mathematician Carl Friedrich Gauss (1777-1855), at a very young age, was told by his teacher to find the sum of the first 100 counting numbers. While his classmates toiled at the problem, Carl simply wrote down a single number and handed the correct answer to his teacher. The young Carl explained that he observed that there were 50 pairs of numbers that each added up to 101. So, the sum of all the numbers must be [tex]$50 \cdot 101 = 5050$[/tex].

Use the method of Gauss to find the sum:
[tex]1 + 2 + 3 + \ldots + 270[/tex]



Answer :

To find the sum [tex]\(1 + 2 + 3 + \ldots + 270\)[/tex] using the method of Carl Friedrich Gauss, we can recognize the pattern and symmetry within the sequence.

### Steps:

1. Identify the sequence and number of terms:
The sequence given is [tex]\(1, 2, 3, \ldots, 270\)[/tex]. This sequence is an arithmetic series with:
- The first term ([tex]\(a_1\)[/tex]) = 1
- The last term ([tex]\(a_n\)[/tex]) = 270
- The total number of terms ([tex]\(n\)[/tex]) = 270

2. Pair the numbers:
Gauss observed that by pairing the first term with the last term, the second term with the second-last term, and so on, each pair would sum to a constant value.

For our sequence, we have pairs such as:
[tex]\[ (1 + 270), (2 + 269), (3 + 268), \ldots, (135 + 136) \][/tex]

3. Calculate the sum of each pair:
Notice that each such pair sums to:
[tex]\[ 1 + 270 = 271, \quad 2 + 269 = 271, \quad 3 + 268 = 271, \quad \ldots, \quad 135 + 136 = 271 \][/tex]
So, each pair has a total sum of [tex]\(271\)[/tex].

4. Determine the number of pairs:
As [tex]\(270\)[/tex] terms are paired, we can divide the total number of terms by 2 to get the number of pairs:
[tex]\[ \frac{270}{2} = 135 \][/tex]

5. Compute the total sum:
The total sum of the sequence is the number of pairs multiplied by the sum of each pair:
[tex]\[ 135 \times 271 = 36585 \][/tex]

Thus, the sum of the sequence from 1 to 270 is:
[tex]\[ \boxed{36585} \][/tex]