You see seven sisters standing around the kitchen table. Every sister has her own backpack. In each backpack there are seven large cats. And guess what! For every big cat there are also seven small kittens. The question is - how many legs are in the room?

The seven sisters have 14 legs all together

The kitchen table could have any number of legs, so I will not count that

seven large cats have 28 legs, times 7 for each sister having 7 cats, that's 198

for each of the 49 large cats there are 7 small ones making 343 cats, but 1372 legs

add 1372+14+198=1584 legs. (not including however many legs are on the table they are standing around)

The only problem:

It is not possible to fit 343 small cats and 7 large cats in just 7 backpacks.