where 
the formula looks like this with the terms in order the initial outlay is multiplied by 1 because it is money being subtracted from the project using the above examples the company can calculate irr for each project in each term irr must be substituted with an educated guess because the only way to determine the best irr is through trial and error you can see how this can become manually tedious and prone to errors using these same values in a spreadsheet you can use this function 