Have you tried "playing" store with him? Sounds weird, but it works.
I'm no math whiz myself and never was. But my grandma was determined to teach me the value of money and started in on me as soon as I was about 2 yrs. If she was going to buy something for me (usually under a dollar) she'd hold out a dollar's worth of change in her hand. I had to pick out the correct coins in order to get the prize. By the time I was in kindergarden I could not only do this....but shop for bargains......and add in sales tax to be certain my total would always land within that dollar limit.
Weird part of that is that I can still do it. But now it's with any amount of money. Give me limit, set me loose shopping, and the total of what I buy will be within 50 cents of that limit, sales tax included.
Because I learned it so young.......I do it subconsciously and can't even tell you how I do it. But now all my math has to be thought of as "money" or I can't do it.
Ok. I'm a freak.
Hmmmmmmm. Have you tried setting out several dollar bills on a table. Set 4 quarters next to the first one, set 10 dimes next to the 2nd one, 20 nickels next to the 3rd one, and 100 pennies at the last one. Then make a new set for coins. Take a quarter and place 2 dimes and a nickle next to it. Take another quarter and place 5 nickels next to it. Take another quarter and place 25 pennies next to it.
With this base to show him the "worth" of both dollars and coins you could visually ask him to add the change. Tell him you want 27 cents. Have him choose the right coins to hand to you that will give you that amount. Do not have him write it on paper until he can do it with the coins. Once he gives you the right amount with the coins.....then ask him to try to write it down on paper. Might take many tries before he gets it.
Math......especially money, used to scare me to death in school. Sounds stupid, but I recall being in like 2nd grade and doing the stuff and they'd show pictures of money in the math books and you were supposed to add them up and such and I could
NOT get it. I had to pretend I was buying something or it didn't make sense. And usually, I had to close my eyes and visualize real money changing hands before I could do the problem.
Uh......yeah. I
said I am a freak.