Zero Sense
The ability to be at home with large numbers like millions, billions, trillions, and quadrillions, and not just knowing how many zeros they each have.
Being aware that a million has 6 zeros, a billion has 9 zeros, a trillion has 12 zeros, and a quadrillion has 15 zeros is only the first step; we need to try visualizing the difference between them by putting them into context—we need that zero sense to get a feel of what these numbers represent.