Simone Biles performs on the balance beam during the artistic gymnastics women’s team final on Tuesday. (Rebecca Blackwell/Associated Press)

Millions will tune in to see who will win the women’s all-around at the Rio Olympics on Thursday, but none should expect to see a perfect 10. Those days are gone, thanks to a revised scoring system that world gymnastics implemented 10 years ago in an effort to make the process less subjective and more fair.

In place of the old scoring system that graded gymnasts on a single 10-point scale for how well they executed their routines is a two-pronged method that now accounts for both the routine’s execution and its difficulty. It’s these two independently judged numbers added together that comprise the more complicated scores of today. That’s why Simone Biles, for instance, can score 15.733 on the floor, her signature event.

Let’s break it down further.

Biles, who does things no gymnast before her has, employs a floor routine that boasts one of the highest starting difficulty scores, at 6.8. Those points make up the baseline of the score, meaning that even if Biles faltered on all of the routine’s elements, she’d still be assured at least 6.8 points. Starting with such a high difficulty score, or D-score, is actually one of the reason why Biles is so unbeatable; most other gymnasts start with D-scores no higher than 6.5.

Simone Biles competes in floor exercise Tuesday as part of the Olympic team competition. (Damir Sagolj/Reuters)

Where gymnasts with less skill and more grace can make up points is in the execution score, or E-score, which starts at 10 points and drops depending on deductions. For instance, stepping out of bounds on the floor is a deduction. Hopping on the landing is a deduction. Even seemingly unnoticeable things, such as not keeping your knees perfectly together or your toes pointed enough, can account for deductions, which is why neither Biles nor any other gymnast in the new-points era has ever scored a 10 for execution. Biles, who executed her floor routine as well as anyone could have during the qualifying rounds Sunday, had an E-score of 8.933.

Unlike the old system, which almost entirely valued perfection in a routine, the new system puts more emphasis on riskiness and evolution of acrobatics.

“One mistake doesn’t change everything for Simone,” the NBC commentators said of the 19-year-old gymnast Sunday while the judges mulled over her E-score. “She can make several and she can still be in the lead, even at the Olympic games.”

“Yes,” another commentator said. “She’s fallen off an apparatus or stepped out of bounds and still won easily.”

That wouldn’t be possible under the old scoring system, which put no special value on increasingly difficult skills. Take Mary Lou Retton’s perfect-10 vault, for instance. The only American ever to earn a perfect 10, Retton executed a full-twisting Tsukhahara, which in today’s scoring world carries a difficulty rating of 5.2. Even with zero deductions for execution, Retton’s score would top out at 15.200, which would put her in fourth place among the gymnasts who competed in the qualifying vault event Sunday. Biles topped the scores with a whopping 16.050, thanks to a higher starting D-score of 6.4 and a nearly perfect execution score.

If anyone is poised to capture a perfect 10 execution score, it’s Biles. If she does it, she’ll be the first gymnast to get a perfect 10 E-score under the new code of points and the first to receive a 10 under either scoring system since Romania’s Lavinia Milosovici and China’s Li Lu, who both scored perfect 10s under the old system at the Barcelona Olympics in 1992.