9,999,999 Simolens bug

I have a standard family, I played the game without any money cheats (just testing and moving objects).

When I earned around 160,000 simoleons, I put all the family items in my inventory and moved to a new house (the second most expensive in the base world).

The problem (if I can call it that) is that I was credited with 9,999,999 simoleons.

Does anyone know why?

Thanks for your tips!