Unfortunately, in a rather irritating case of genre-savviness, the bomb was, in fact, designed to go as soon as it was successfully disarmed, and now Rainbow's home is entirely flooded in strawberry jam. That hungers for pony flesh. As jam does.
While the cleaners are trying to hoover it all up, Rainbow plots her revenge. Unfortunately, most of the budget for the prank war went into the purchase of the Prism Poppers, and so you're pretty much on a shoestring. Fortunately, Rainbow does at least have one idea, considered by many to be the most heinous scheme ever conceived: spam her letterbox. As it happens, Wonderbolts such as herself receive a lot of fanmail, and she in turn has access to a lot of stamps, letters and other items to reply to any at any time back at the Wonderbolt Academy. She therefore decides to mail Black Bird a series of seemingly useless letters, filled with only seven digit numbers, direct to her mailbox, in different fonts from a typewriter, so she doesn't realise they are from the same pony, and hopefully either it will annoy her, receiving so much junk all at once, or result in her ignoring an important tax bill out of sheer frustration and get arrested for fraud, or something.
Gathering together all the supplies she got from the Academy for free, she decides to keep you occupied with a puzzle, to keep you from going stir crazy writing out idiotic letters. She's writing down different strings of seven numbers, basically to see if Black Bird tries to find meaning in these numbers that doesn't actually exist, but what Rainbow wants to know is: if she had some sort of machine that randomly assigns seven figure numbers to each of you, what are the chances both of you would wind up with an exact scramble of the other - that is to say, each number appears with the exact same frequency, but in a different order from the other? Basically, if 5 appears three times in Rainbow's number, it will appear three times in yours as well.