1, 2, 3, 4, 5, 6, 7, 8, 9, ⵒ, Ɛ, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 1ⵒ, 1Ɛ, 20!
Simple!
Compare how long it takes you to answer these questions:
How many centimeters are there in 17 and a half meters?
How many inches are there in 17 and a half feet?