###Human: If a rectangle has a width of 42 inches and an area of 1638, how many rectangles of the same size would reach a length of 390 inches?, ### Assistant: The rectangle has a length of 1638 in/ 42in = 39 in.
The number of rectangles required to reach 390 inches is 390/39 = 10 rectangles. 
 So the answer is :  10