' FB 1.05.0 Win64

Randomize
Dim a(1 To 20, 1 To 20) As Integer
For i As Integer = 1 To 20
  For j As Integer = 1 To 20
    a(i, j) = Int(Rnd * 20) + 1
  Next j
Next i

For i As Integer = 1 To 20
  For j As Integer = 1 To 20
    Print Using "##"; a(i, j);
    Print " ";
    If a(i, j) = 20 Then Exit For, For '' Exits both for loops
  Next j
  Print
Next i

Print
Print "Press any key to quit"
Sleep