Meghan Trainor has pumped out some pretty terrific jams and she knows a thing or two about creating them.

Meghan's debut album Title shot to #1 on the Billboard 200 chart the week of its release and she has two Grammy nominations under her belt -- NBD. In case you forgot, she's only 21 years old.

"Do you know what a hit song sounds like now?" radio host Zach Sang asked Meghan in a recent interview, "Mhm. I know the formula. I could teach someone the formula," she answered confidently. “I can teach someone how to do a pop song… Structure can be taught. Everything else is what you got."

There's a science behind Meghan's tracks -- a set of criteria she follows in order to create an earworm.

So, what makes a song a smash? Here's what Meghan revealed:

The song has to be timeless.

"I think the greatest songs are the ones that are timeless," Meghan admitted, "The ones that I can write now and in 60 years they will want to play it in their house and they will still jam to as if it was brand new -- that's a smash. That's the first rule, timeless."

Melody is everything.

"The catchier it is the more they're going to play it. If they hate it that's a hit, you know? Because they're just playing it too much. Remember 'Rolling In The Deep'? The radio killed that song. That's a smash."

Appeal to the young and the old.

"The hit that spreads around the world the quickest is the one that toddlers will dance to and the one that older generations will dance to," Meghan has found. "Because in that household the parents and the siblings must listen to it because this toddler is like, 'Bass, bass, bass,' just begging for that song. And the older generation is like, 'Kids, you've got to check out this new girl. I've discovered her,' and they feel cool and they're showing their entire family. Mothers love me. That's when you win the most. When you not only get 13 year olds and not only just get 20 bad ass girls that are like away from their parents right now, you know? You get everybody."

Take music from the past and make it current.

“Everything has pretty much been done. So now all we can do is take our influences and try to make them modern and make them relatable and then better. That’s what I’m doing. I’m taking those timeless hits, that if I sang them to you right now you would know every word," Meghan revealed, "I’ve put my own flavor of urban soca love on that and then lyrically I talk about texting and face tune and all the young generation stuffs and then I just put a little bow on it and I give it to the world and they’re like ‘What is this? This is new!’”