$\bg_white \\*\emph{\text{ In how many ways can you select }}7 \emph{\text{ letters from the word MISSISSIPPIRIVER regardless of their orders }}?$

In how many ways can you select 7 letters from the word MISSISSIPPIRIVER regardless of their orders?

Algebra
In how many ways can you select 7 letters from the word MISSISSIPPIRIVER regardless of their orders?