You want to use square tiles to cover the top of a table you're making. the top is 30 inches by 18 inches. what is the side measure of the largest-sized square tile you can use to cover the tabletop without any overlap or cutting?

You can use greatest common factor(gcf)
list the factors of 18 and 30.
18- 1, 2, 3, 6, 9, 18
30- 1, 2, 3, 5, 6, 10, 15, 30
now the factor that is greatest is 6.
this mean you can use the largest square tile of 6in by 6in without overlap or cutting.