We often play this Numbers Memory Game with Adrian. As an extension, or as a child gets older, you can use larger numbers, and/or incorporate color in the memorization process. Thus, a child, besides having to remember the correct number of counters to retrieve, also has to remember the color of marbles. It is a lot of fun: I would place baskets in different parts of the house, so Adrian gets plenty of running around, while training his memory:)
We are using the same colored marbles as (here) and numerals from a clock which happened to come in different colors. You can use colored bead or poker chips and mark the number with a colored dot and then a toddler needs to bring back for example: four blue marbles if number four was color-coded blue. As a result, a child has to remember the numeral and the color.
Then, leaving the numeral on the table, Adrian would go to the other side of the house, where counters (marbles) are located, and he has to bring back the exact amount of marbles of the same color as the numeral from the bag.
Here, he picked number "5" in Blue, so he had to bring back five blue counters/marbles.
Apparently, he had to go and use the bathroom (a little detour), so it took longer, and in the process, he forgot how many marbles he was supposed to bring back.