I think a quarter sheet cake is 9 x 12, which is 108 sq inches. If you think your Id google, 1/4 sheet cake feeds how many and click images.
Sheet cakes come in different sizes because of the many different pans Crocker) is the quarter sheet pan, which measures approximately 9" x.
Per several requests to post this here, here it is. This is the guide that I created to determine how many servings per each sheet cake and a diagram of how I.