# A sigma notation but with multiplication instead of addition?

I am not a mathematician, so I apologize if this question will sound stupid. I am wondering is there some sort of notation which will resemble the one of sigma notation, but with multiplication instead of addition?

For example, the following expression: $2^1+2^2+2^3+2^4+2^5$ could be written as: $\sum_{i = 1} ^ 5 2^i$

But what about the following expression: $2^1*2^2*2^3*2^4*2^5$ ?

Is there some notation like sum sigma that could enable me to write this last expression a bit shorter?

Thank you very much.

• $\prod$ $$\prod_{k=1}^5 2^k$$ – Daniel Fischer Aug 7 '14 at 22:19
• This may already be obvious to you, but I'll leave it here anyway: S is for sum, P is for product. Sigma and pi are the Greek letters for S and P. – Rahul Aug 7 '14 at 22:51
• Amusingly, you can do without a new notation, because $2^1\cdot2^2\cdot2^3\cdot2^4\cdot2^5$ is $$2^{1+2+3+4+5}=2^{\sum_{i=1}^5i}.$$ – Yves Daoust Aug 7 '14 at 23:02

You can use Pi notation (The $\LaTeX$ for this being \prod)
$$\prod\limits_{i = 1}^5 2^i = 2^1 \cdot 2^2 \cdot 2^3 \cdot 2^4 \cdot 2^5$$