Put 9 egg tarts, 3 in each row, and the radius of each egg tart is:

12/3/2=2

Egg tart area: 3.14 * 2 * 2 * 9 = 3.14× 36.

Put 16 egg tarts, 4 in each row, and the radius of egg tarts is:

12/4/2= 1.5

The area of egg tart is 3.14 *1.5 *1.5 *16 = 3.14× 36.

The area of the egg tart is equal, and the blank of the first one is equal to the blank of the second one.

It's 100%