10 INPUT "Size? ";rows;"*";columns
20 DIM a(rows,columns): REM defines a numeric array
30 LET a=INT (RND*rows)+1: LET c=INT (RND*columns+1): REM the array is labelled a, but the letter a is still available for variable assignment
40 LET a(a,c)=1
50 PRINT a(a,c)
60 DIM a(1): REM arrays cannot be removed without CLEARing the entire variable space, but redimensioning them to 1 will save most of the space they used