better calc

<?php

    protected $num = 0;

    public function add($int)
    {
        if ($this->isInRange($int)
            $this->num += $int;

        return $this;
    }

    public function sub($int)
    {
        if ($this->isInRange($int)
            $this->num -= $int;

        return $this;
    }

    public function mult($int)
    {
        if ($this->isInRange($int)
            $this->num *= $int;

        return $this;
    }

    public function div($int)
    {
        if ($this->isInRange($int)
            $this->num /= $int;

        return $this;
    }

    public function getTotal()
    {
        return $this->num;
    }

    public function isInRange()
    {
        // could be the same as my validatePositiveInts() method I guess....
        // yeah, this would work a hell of a lot better, i DID NOT include
        // error exceptions though, but we could use some of it from my
        // calc method, and even work it farther down to type detect for a
        // more specific error.... show your guys this too maybe? should have
        // though it over for a few more minutes ;)
    }