A customer service representative from Singapore Airlines told them they "hit the jackpot." (Pictured: Pedro Pla, Grace Cheng, and their 2 sons). Courtesy of Pedro Pla Travel has always been a part of Pedro Pla's life. By the time the Puerto Rican was three years old, he'd visited as many continents.

In 2007, Pla, now 35, and his Singaporean wife Grace Cheng, 36, embarked on a year-long journey around the world, traveling to 15 countries on five continents using two Round-The-World (RTW) economy tickets they'd purchased for around $10,000 through OneWorld, the network that comprises 15 international airlines.

To mark the 10th anniversary of their journey, the couple, now joined by their two sons, 4-year-old Ramses and 2-year-old Ranefer, set out on another trip around the world in January — but this time they got their tickets almost completely for free.

In September 2016, Pla and Cheng, who are the cofounders of credit-card comparison site Get.com, hit 1 million airline miles after a year of racking up credit card rewards points. They redeemed 960,000 miles, worth a total of $54,000 (though they had to cover taxes and fees), through Singapore Airlines' frequent flyer program, KrisFlyer, to purchase four RTW business class tickets.

Singapore Airlines is part of the Star Alliance network, which has more than two dozen regional and international carriers. The RTW ticket allows travel on any airline in the network, up to 35,000 miles in a continuous Eastbound or Westbound direction on 16 separate flights. The cost of a RTW ticket can vary depending on the flight class, country of origin, and total mileage of the trip. Tickets can be purchased in cash or redeemed through points and can only be booked over the phone.

On their six-month trip, the family is traveling to five continents and at least 15 countries, including Kenya, Switzerland, Argentina, Colombia, and South Korea.

"While booking our Round-The-World flights with SIA, its customer service representative told us we had 'hit the jackpot' as they had never encountered anyone redeeming for RTW award tickets on business class before, let alone for four people," Pla told Business Insider in an email.

He said they had to "research and plan meticulously" to reach their points goal.

"As credit card geeks, we live by this maxim: When you use cash, you lose cash. Using cash means you are missing out on getting credit card rewards points, miles or cash back. We used our credit cards to pay for everything if possible, be it a hamburger or an air ticket," Pla said.

Read on to learn more about the RTW program, exactly how the family racked up their rewards points, and their best advice for travel hacking.

Follow the family's Round-The-World journey on their Instagram or Get.com.