{
   my $saved_option = 10; # default value is 10
   sub options{
      # were we passed a value to save for later?
      if (@_) {
         $saved_option = shift;
      }
      return $saved_option
   }
}
[download]

my $option = 10;
while (1) {
   print"choose 1  or 2 \n";
   my $choice=(<STDIN>) or last;
   if ($choice == 1) {
      &flashcard($option);
   }
   elsif ($choice == 2) {
      print"enter  random range\n";
      my $option = (<STDIN>);
   }
   else {
      last
   }
}

sub flashcard {
   my $option = shift;
   my $random = int(rand($option));
   # do stuff with $random
}
[download]

Here is the initial code

use warnings;
use strict;
print "Welcome to Multiplication Challenge\n";
print "What would you like to do?\n";
print "1) FLASHCARD MODE\n";
print "2) TEST MODE\n";
print "3) OPTIONS\n";
print "4) Exit\n";
my $input = undef;
my $max   = undef;
my $min   = 10;

sub menu {
    print "What would you like to do?\n";
    print "1) FLASHCARD MODE\n";
    print "2) TEST MODE\n";
    print "3) OPTIONS\n";
    print "4) Exit\n";
}
while ( $input = (<STDIN>) ) {
    if ( $input =~ /1/ ) {
        print "FLASHCARD MODE\n";
        flashcard();
    }
    elsif ( $input =~ /2/ ) {
        print "TEST MODE\n";
        testmode();
    }
    elsif ( $input =~ /3/ ) {
        print "3\n";
        print "What is the maximum number?\n";
        my $max = (<STDIN>);
        &makeitbig($max);
        &menu();
    }
    elsif ( $input =~ /4/ ) {
        really();
    }

}

sub really {
    print "Are you sure?\n";
    my $input = (<STDIN>);
    if ( $input =~ /y/ ) {
        exit;
    }
    else {
        menu();
    }
}

sub flashcard {
    for ( 1 .. 10 ) {
        my $random1 = int( rand(10) );
        my $random2 = int( rand(10) );
        print "$random1 *  $random2\n";
        my $total = ( $random1 * $random2 );
        &validate($total);
    }
}
my $count = 1;

sub validate {
    my $newdata = shift;
  TRYAGAIN:
    my $input = (<STDIN>);
    if ( $input == $newdata ) {
        print "Correct!\n";
        $count++;
        if ( $count == 10 ) {
            print "Congratulations\n";
            print "You have finished FLASHCARD MODE;\n";
            menu();
        }
    }
    else {
        print "$count: Try again\n";
        goto TRYAGAIN;
    }
}

sub testmode {
    for ( 1 .. 25 ) {
        my $random1 = int( rand(10) );
        my $random2 = int( rand(10) );
        print "Problem  '#'$_\n";
        print "$random1 * $random2\n";
        my $total = ( $random1 * $random2 );
        &validate_low($total);
    }
}
my $meter         = 1;
my @correct       = ();
my $correctanswer = 1;

sub validate_low {
    my $newdata = shift;
    my $input   = (<STDIN>);
    $meter++;
    if ( $input == $newdata ) {
        print "Correct!\n";
        push( @correct, $correctanswer );
    }
    else {
        print "Sorry!\n";
    }
    if ( $meter == 25 ) {
        &calculate();
    }
}

my $sum = 0;

sub calculate {
    foreach (@correct) {
        $sum += $_;
        return $sum;
    }

    my $prcnt = 4 * $sum;
    print "You got $sum answers correctly out of 25. This is $prcnt%\n
+";
}

sub makeitbig {
    my $other = shift;
    if ( $other == $min ) {
        return $min;
    }
    else {
        return $other;
    }
}
[download]

rand returns a random¹, uniformly distributed number. To quote the documents, "Returns a random fractional number greater than or equal to 0 and less than the value of EXPR. (EXPR should be positive.) If EXPR is omitted, the value 1 is used. Currently EXPR with the value 0 is also special-cased as 1 - this has not been documented before perl 5.8.0 and is subject to change in future versions of perl."

So, if you pass 0 to rand(), it currently returns a value, x|0 ≤ x < 1. I believe it does the same think if you pass undef to rand, but RTFM². How you handle your value of number (incidentally,

$my number = 10;
[download]

my $number = 10;
[download]

$value = $user_input or 10;
$x = rand($value);
[download]

Now, if you want to guarantee that rand always returns the same sequence of values, you've got to explicitly seed it, using srand. Once.

²The manual is definitely a worthwhile read, too. As an old connoisseur of computing documents, Perl's is definitely deserving of accolades.

I don't know what you are trying to do. "set the initial rand input" makes no sense. Could you clarify? In the meaning time, check out these problems with your code.