Task

Produce a formatted   12×12   multiplication table of the kind memorized by rote when in primary (or elementary) school.



Only print the top half triangle of products.




 
(lib 'matrix)
 
(define (mtable i j)
    (cond
    ((and (zero? i) (zero? j)) "😅")
    ((= i 0) j)
    ((= j 0) i)
    ((>= j i ) (* i j ))
    (else " ")))
 
(array-print (build-array 13 13 mtable))
 
 