Friday's solutions: Exercise 1: plan: add y to the result x times (define slow-mul (lambda (x y) (if (= x 0) 0 (+ y (slow-mul (- x 1) y))))) Exercise 2: plan: write a procedure that calls itself no matter what (define loop (lambda () (loop))) Exercise 3: plan: if the number is less than 10, it has one digit otherwise it has 1 digit for every time it can be divided by 10 (define num-digits (lambda (x) (if (< x 10) 1 (+ 1 (num-digits (/ x 10))))))