Sigma notation

Sigma notation is a compact way to write a sum of a sequence of numbers. It uses the Greek letter sigma (∑) to represent addition, with a starting point and an ending point indicating which terms to include. For example, ∑ₙ=1^3 n means add the numbers from n=1 to n=3, so 1 + 2 + 3 = 6. It helps organize complex sums efficiently, especially when dealing with many terms or patterns, making calculations clearer and more manageable.