Answer: The box under 1000 is 1, because there are 1000 milliliters in 1 liter. your next box would be 6000, the box above 8 is 8000, and above 9 is 9000. Does this make sense? I hope so.
Answer:
ML: 1,000 | 6,000 | 8,000 | 9,000
L: 1 | 6 | 8 | 9
I hope this helps :)
