I do not own KHR that would be Akira Amano, and my physics skills come from taking Physics 1. I did actually talk the physics portion out with my teacher to make sure I didn't mess it up, so yes, that is actual physics. Yes, you can calculate arc tangent without a calculator (I can't do it). Those are also all of the variables I could think of that Skull would need to calculate for a somewhat basic stunt (Jumping from one ramp to the next with three mid-air spins)

Skull refrained from rubbing his hands down his face and accidentally smearing his makeup. He pointedly did not look at the arguing duo at the head of the dark wood table that most of the Il Prescetti Sette were gathered around. He had never envied someone as much as he currently envied Luce who was away on Giglio Nero business.

"We can't shoot them from below, the angle's too high!"

"What about the other side of the building? Someone needs to be sniping on that side as well, otherwise there will be more for Fon and Viper to deal with."

Fon and Viper paused a moment in their quiet discussions of their half of the job at the sound of their names. When Lal and René continued their argument, the two continued hashing out their plan to retrieve the stolen information.

Skull watched Verde scribble notes and calculations in his notebook with a bored fascination. "Just snipe from the roof," he said tonelessly.

"Yes, that would be effective," Lal drawled. "Shooting blindly through building materials, great plan, lackey."

Skull rolled his eyes, meeting Verde's green eyes for a moment when Verde raised his from the notebook in front of him. "From the roofs of adjacent buildings, not the roof of the target building." Skull shifted in his seat. His hands clasped together, and he leaned over his arms. "They're far enough away that the angle is insignificant."

"And how would you know this, lackey?" René asked, crossing his arms over his chest. His face was hidden by his fedora.

"Can I have a paper, Verde, please?" Skull reached a hand across the table towards Verde.

Verde considered Skull over his glasses before he silently tore a piece of paper from his notebook. He passed the paper over to Skull who gave Verde a small smile as he pulled the paper in front of him.

Skull pulled a marker out of his jacket pocket, drawing two buildings on the paper with a horizontal line drawn between them at where he had drawn the third windows going up the buildings. "The buildings are about one city block apart," he began. "That's about 80.4 meters." He wrote the number on the horizontal line. René and Lal walked over and stood behind Skull, leaning over his shoulders as he continued, "The targets are expected to be on the third floor which is one story down from the roof, 3.33 meters difference in height." Skull wrote the height down beside the building to the left above the horizontal line. He then drew a diagonal line from the top of the left building to where the horizontal line met the other building. "The angle," he said, drawing a half circle in the vertex where the lines met, "is simply the arc tangent of 3.33 over 80.4." Skull scribbled out the calculations for finding the arc tangent. "Which is 2.37 degrees."

René started checking the math, mouthing the numbers as he did so. Skull looked over his shoulder at the designated snipers. "The bullet would also drop a small amount, so if you aim for the forehead it would go through their nose. Still dead, but…" He shrugged.

René stopped at the end of the paper. He exchanged a wide-eyed look with Lal, his fedora having slid back enough to see his face. "The math's right," he said.

"Of course it is," Verde said, pushing his glasses up his nose and glaring at the two. "He's a stuntman."

"And what does that have to do with this?" Lal snapped.

"I have to calculate my own stunts," Skull said. "I have to account for the acceleration up a ramp, how many flips I do in mid-air, my own mass as well as the mass of the bike, how much energy I regain when I land on the second ramp, how much speed I gain going down, how much speed I lose to drag, and the exact moments I need to shift my weight to begin and end the flips." He pushed back from the table, causing René and Lal moved to either side.

Skull stood up and turned to them with a closed smile. "But I'm just the lackey. Espresso, I assume?"

AN: My theory is that neither Reborn or Lal are professional snipers. They just know the basics and at this point are still establishing the pecking order, hence the somewhat OOC argument that frames this.