How do you do this?

/prog/ How do you do this?

Write the function mult-table which consumes two natural numbers nr and nc, and produces a list of nr lists, each of which contains nc natural numbers. The cth entry of the rth list (where we start numbering at 0) in the produced list should be r*c.
For example,
     (mult-table 2 3) => (list (list 0 0 0) (list 0 1 2))
and
     (mult-table 3 4) =>
        (list (list 0 0 0 0)
              (list 0 1 2 3)
(list 0 2 4 6)).
Hint: use build-list twice. The first time, try to make a list containing nr elements. Then, for each of these elements, make a list of nc elements. You may use other abstract list functions as well.

Here's my solution.

(define (mult-table nr nc)
  (define (iter-table r)
    (define (iter-row c)
      (if (< c nc)
        (cons (* r c)
              (iter-row (+ c 1)))
        '()))
    (if (< r nr)
      (cons (iter-row 0)
            (iter-table (+ r 1)))
      '()))
  (iter-table 0))

Of course, this doesn't use the build-list procedure you're supposed to use, because you provide it, so you probably won't get full credit.

What school are you attending that teaches Scheme?