1. The problem is to find the sum of the numbers: 1, 2, 3, 4, 5. 2. The formula for the sum of the first $n$ natural numbers is: $$ S = \frac{n(n+1)}{2} $$ where $S$ is the sum and $n$ is the last number in the sequence. 3. Here, $n = 5$, so substitute into the formula: $$ S = \frac{5(5+1)}{2} $$ 4. Simplify inside the parentheses: $$ S = \frac{5 \times 6}{2} $$ 5. Multiply numerator: $$ S = \frac{30}{2} $$ 6. Simplify the fraction by canceling common factors: $$ S = \frac{\cancel{30}}{\cancel{2}} = 15 $$ 7. Therefore, the sum of the numbers 1 through 5 is 15.