Mrs. smith has bolts of material that have lengths of 42, 63, and 105 inches. she needs to cut the fabric into equal length pieces with none left over. what is the greatest length of fabric pieces she can cut?

To answer the question above, factor each number and determine the biggest common factor. 
 
                                    42 = 6 x 7
                                    63 = 9 x 7
                                    105 = 15 x 7

The common factor for these numbers is 7. Thus, the fabric pieces should be 7 inches long.