The problem is that you are reversing the string a few times. The following will do: (defun base8 (n) (let ((t8 (truncate n 8)) (m8 (mod n 8))) (if (= t8 0) (list m8) (append (base8 t8) (list m8))))) EDIT Here's a solution without append, using a helper function.
On average, a kidney weighs approximately 150 to 160 grams and, together, both kidneys weigh about 0.5 percent of total body weight. Usually, the left kidney is slightly larger than the right. These measurements and weights represent the typical ranges of a healthy, adult human kidney.
What is the average kidney size? The development or increase in the size of this organ stops at the age of 25 or 26. When the kidney stops to increase in size, the average length usually reaches 12 centimeters while the breadth is approximately 6 centimeters. The mean thickness of this body part is around 3 centimeters. The mean weight of a kidney is 120 grams to 150 grams. With these dimensions, any decrease in the kidney size is abnormal. However, the size of a kidney can still grow after maturation. This can happen if one of the kidneys was removed.