Step 1:

Find out number of requirements.

Step 2:

Find out number of test cases.

Step 3:

Create a table based on these. Let we have 10 requirements and 40 test cases, then we create a table of 11 rows and 41 columns.

Step 4:

On the first column of table copy all your 10 requirement numbers, and paste them into rows 2 through 11 of the table.

Step 5:

Now copy all 40 test case numbers, and paste them into columns 2 through 41 of the table.

Step 6:

Examine each of your 40 test cases, determine which of the 10 requirements they satisfy.