I recently attended a working memory workshop. The main strategy to help with working memory, as the title to this entry says: "Repeat, Break it down, Chunk it up, Repeat".
In one of the sessions with my students, I witness the immense help chunking information, especially numbers, helped in the processing of that information. We were reading numbers to the thousands, and by chunking the number into 3 digits starting from the right, it was clear that any digit that falls into the next lot of 3 would be in the thousands. For example, the number 34987, when chunked, would look like 34 987.It can be seen clearly that 34 is in the thousands place. Therefore, this number would be read as thirty four thousand, nine hundred and eighty seven.
This can be extended into the millions and billions. I call this the rule of 3. :)