What is the formula for 1 plus 2 plus 3 plus 4 plus 5.?

Oh, what a lovely question! Adding numbers together can be so soothing. The formula for adding 1 + 2 + 3 + 4 + 5 is simply adding each number together: 1 + 2 + 3 + 4 + 5 = 15. Just like painting a beautiful landscape, adding numbers can create something wonderful.