$my number =10;                      XXX Invalid syntax
while($input=<STDIN>){               XXX Input a value that's never used.
print"choose 1  or 2 \n";            XXX Extra space in prompt.
$choice=(<STDIN>);                   XXX Improperly localized. Use 'my'. Error revealed using 'use strict';
if($choice=~/1/){                    XXX Allows more than intended, such as 37612.
&flashcard();                        XXX Misleading use of "&". Get rid of it.
else{
 $choice=~/2/);                      XXX Allows more than intended, such as 37612.
 print"enter  random range\n";       XXX Extra space in prompt.
 my $newrandom = (<STDIN>);
 &options($newrandom);               XXX Misleading use of "&". Get rid of it.
                                     XXX Useless call to function since it has no side-effects and you discard the result.
  }
}
sub flashcard {
my $random = int(rand(&options()));  XXX Misleading use of "&". Get rid of it.
                                     XXX options() expects an argument.
}
sub options {

my $max = shift;
if ($max==10){
    return 10;
}else{
  return $max;
    }
}                                    XXX Your code is unreadable throughout due to inconsistent and nearly non-existing indenting.