These two symbols, generally speaking, σ is the sum of several numbers and π (capital π) is the product of several numbers.

See here, the symbol above represents the final value of n (I named it myself, it doesn't matter), the following represents the initial value, and the algebraic expression is on the right. Together, that is to say, n takes 1 to ∞ (infinity. Of course, infinity can't be taken down, that is, it must always be taken down. If you change the above to 6, add it to 1/6 square. (The squares are garbled, so I will use Chinese characters. You should know what the square here means! )

π is used in the same way, but it represents the multiplication of terms.

Let me give you a few more examples.

The premise of this is xi(i is the lower corner of X, indicating the order).

A is a set. A set is just a whole composed of some numbers. For example, {1, 2,3} represents a set with three numbers 1, 2,3? This formula means that the algebraic number in set A is calculated in the algebraic expression and then multiplied (don't worry about the result, I just cut a part of the graph). The symbol between P and A is read as belonging, which means that the number P belongs to the set A, that is to say, P takes its value from the set A..

This means adding from 1 to n. If n=3, the answer is 6. Do you think it's right?

It's not bad for primary school students to have such ambitions! If you are interested, you can add it? QQ: 1934878329, I like math, too!