May I suggest Montessori Arithmetic materials? A few articles from a Montessori publication on this topic may give you great insight for showing him math.
And practice using terms like;
~ eggs and
a great omelet
~ eggs plus
bag of mix equals
~I need that scoop of detergent two times
, (Why mom? because this muddy load is going to go through an extra long wash cycle w/ an extra rinse! So, it needs more detergent.)
~Or from that scoop we need just 1/2
for our 1/2
load, so lets divide equally
Keep up the terms. The more often he hears and experiences them, it'll click.
Play LCR. Find this dice game at Target. You pass objects Left, Center, Right. The objects you use are up to you. Marbles, GI Joes, hotwheels, nickles, pennies, dollars. It comes with little chips. You will have fun with this with adults as well as children, even adults and children playing together. Plus, they all get to practice lefts and rights.
Shopping helps so much, especially if he brings some money to spend. (Its great help if they bring a little notebook with them so they can take notes.) I do this, and when they need more money, I reflect with them how much more they will need for that. Do the same for less. For example: If it is $3.96, and he has $2.50. I would draw out five dollars and explain briefly how the item is only four cents from a whole other dollar, which is $4, see? So, once you get another whole dollar plus half of another, you will have the same as what this "transformer" costs. I like to show the extra dollar just in case he would like to wonder passed exactly what he needs. (hoping he will see he could save even more and have more choices) Then I would paraphrase maybe on the way out....Hey Brandon, so once you add a dollar fifty to your two fifty you will have the four dollars you need for that toy you want.
If you are going to incorporate a calculator, then he would need to understand how to read the equation. Which isn't a bad thing, after he understands what all the values and symbols mean.
Momma, once you can use what he is interested in to reveal where math plays a part (cause it's pretty much everywhere) and use the nomenclature/ terms often and just matter of factly...He will begin to relate with math. Be sure that you are comparing without emotion, so he can see for himself and judge for himself. Although it's not a bad idea for him to hear you think aloud to yourself "I don't think that candle is worth the same to me as $15." and "What do you think son?" You may be surprised that he was paying a lot of attention. A discussion, where you are just comparing, is a good experience for him.
Since I have three kids, they've caught on early how if we can find sets of things our money will last longer, aka: can get us more stuff. A set of 4 notepads is way better for us than the sparkly single one that is the same price as a this set. So now, we can get some extra pencils/ pens/ cap erasers/ squishy grip thingies, too.
Good luck with this.