-0.4 should be in between 0 and -0.5, however be as close to -0.5 as possible while not being ON -0.5.
3 4/5 should be in between 3 and 4, so you can split 4/5 into 8/10 which are equal to each other. Then you can pretend to split the 3 and 4 gap into 10 equal pieces. After you split the gap, count 8 parts to the left of 3.
