Question

How many millimetres are there in five and a half litres

Answer 1

$1=1,000 \\ 2=2,000 \\ 3=3,000 \\ 4=4,000 \\ 5=5,000 \\ 1,000/2=500 \\ 5.5=5,000+500=5,000$

There are 5,500 mL in 5 and half liters. 

Answer 2

You are mixing up units; try and see if you read the problem correctly