Every year is the year to start saving money, and 2015 was no different.

How much money do you need to live for 15 years without working? What will give you the highest ROI in a low-interest-rate environment? Would you be better off closing your traditional checking account with its fees and hassle and putting your money in a virtual wallet instead?

Below are the most popular articles Investopedia published in 2015 on questions like these. Some are no brainers, but some may surprise you.

1. What is the size of the average retirement nest egg? There's often a difference between the real and the ideal. Ideally, if you think you will retire at 65, and you live someplace where the average life expectancy is 80, you should have one million dollars saved up! But in reality, most people have a lot less money in the bank for that contingency.

2. How can I avoid paying taxes on my Social Security income? Social Security's minimum benefit is $700 a month, which is not a lot of money in 2015. Even if you draw the maximum amount, you probably want to give as little of it back to the government as possible.

3. How To Fly First Class For Cheap. The title speaks for itself. Why would you destroy your knees and your peace of mind if you don't have to?

4. How to Plan Your Retirement in the Philippines. We've already established that retiring in the Philippines might be a good idea. Now it's time to get down to brass tacks and figure out the devilish details of spending your golden years in a tropical paradise.

5. What Is The Average Salary For An MBA Graduate? Business school or engineering school? You do the math.

6. World's Top 10 Insurance Companies. Insurance companies do a lot more than sell life insurance. The right coverage for you will protect your family and is a good investment. Now you need to find the right company for your individual needs.

7. How a 401(k) Works After Retirement. You know how the 401k works before retirement. But do you know what to do after retirement? Without the right strategy you could be paying more of your money in taxes than necessary.

8. How Safe Is Venmo And Why Is It Free? The most interesting developments in personal finance this year came from the financial technology sector. Venmo clearly piqued our readers' interest: how is it I can transfer money for free over my phone? And why are so many digital natives doing it? Turns out it's both safe and very handy!