Pixar stuck 20,622 balloons on a house to achieve liftoff in its animated Up, which wouldn't come close to doing the trick in real life, writes Nina Shen Rastogi on Slate's Explainer blog. If the old Carl character were using typical party balloons, he'd need somewhere around 9.4 million of them, writes Rastogi.
If Carl used bigger balloons, say 3-footers, he would need far fewer, somewhere around 100,000, according to calculations in Wired. The filmmakers' tech guys, meanwhile, told Ballooning magazine it would take 23.5 million balloons, though they didn't specify size. And if, as in the movie, Carl really intended to rip his house from its foundation using balloon power, forget it. It's just a cartoon, after all.