What Stamps Are These Tiny Ones

All I could come up with is that millions were produced. Depending on size of coupon they came in sheets of about 80-100 and were selling for $10 per sheet quite awhile ago. The number on the coupon is thought to correspond to the product being rationed.

It is likely the number stands for 'size.' So, if the daily ration per person for meat of the bone was 35 grammes, you would need a total of '35'. The design would then be indicative for the type of product.

NSK your explanation is more likely. Good info.

I can find very little on the Belgian coupons. The same image keeps popping up in the few web pages about Belgian rationing. Dutch pages are plenty. However, the systems were not exactly the same.
Dutch coupons are easy to find even in part or whole sheets.

Do they have internet in Belgium? Or is google.be just seeing my IP address and thinking "bugger it mate, here's some Dutch rather than Belgian stuff"?

Google is looking at your IP address. You have to change your location to Belgium (in Google's settings).