No explanation this time. Drop colours in, take them out, and find the number they make. See what you start to notice.
Two things only: notice and play. Nothing to memorise, no right way to begin. Add a colour, make a guess, change your mind. Keep going, and the patterns will come to you.
Tap a colour to drop it in. Tap a disk to take it out. Then guess its number on the grid.
Some numbers can be built. Some can't. That's part of it.
Free puzzles and ideas for playing with numbers, a few minutes at a time.
The colours as real disks to build with on the table, where the noticing happens best.