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.
People are born with two kidneys. Each is about the size of a fist, and they're on both sides of your spine at the bottom of your rib cage. Together they weigh about 10 to 12 ounces. When your body uses the food you eat and the liquids you drink, there are waste products that your kidneys filter out as urine.