How many calories do you burn running a 100 meter sprint?

Not enough to matter in any meaningful way.

You might be pushing hard, but the exercise is too short.

Let's say your all-out effort is 1800 calories/hour.

The sprint might take you 15 seconds. That's 1/240 part of one hour, or about 7.5 calories.

A single cupcake is maybe 400 calories.