How many covariance terms would exist for a portfolio of 10 securities using the Markowitz analysis? How

Question:

How many covariance terms would exist for a of 10 securities using the Markowitz analysis? How many unique covariances?
Portfolio
A portfolio is a grouping of financial assets such as stocks, bonds, commodities, currencies and cash equivalents, as well as their fund counterparts, including mutual, exchange-traded and closed funds. A portfolio can also consist of non-publicly...