It can be confusing for people to remember a lot of formulas, especially if they do not know what to expect. This time, you need to know how to convert meter inverse to a nanometer. A nanometer is just one billionth of a meter so you can already imagine how short this can be.
You need to check out the given numbers first as this will help you in making the right process for solving this. In one unit, there are 10^(-9) meters/nanometer. You need to convert the inverse meter to the inverse nanometer then multiply it. Another process is if you would divide the number by a billion so that you can get the right answer.