Answer:
4.2
Step-by-step explanation:
The square root of 18 is 4.24
So, on this number line, it should go about 1 cm away from 4 to indicate that it is not 4, but 4.2.
Put the dot where you think it would be appropriate to be labled as 4.2.
Also if you didnt know the x axis is the one on the bottom.