500) { echo '' . "$a + $b = $suma
" . ''; } if ($suma >=250 && $suma <=500) { echo '' . "$a + $b = $suma
" . ''; } if ($suma <250) { echo "$a + $b = $suma
"; } break; case "resta": echo "$a - $b = "; while($b-- != 0) { $a--; } { echo "$a
"; } break; case "multiplicar": for ($x = $a * $b; $x > 0; $x -= $a) echo "$x
"; } ?>