What is to be subtracted from 5.1 to get 0.51?

1. 0.44
2. 0.99
3. 4.59
4. 5.49

Let the required number be x.

5.1 - x = 0.51

x = 5.1 - 0.51

x = 5.10 - 0.51 = 4.59

Hence, option 3 is the correct option.