Calculate it

There is a bus with 7 children inside. Each child has 7 bags. Inside each bag there are 7 big cats. Each big cat has 7 small cats. All cats have 4 legs each. How many legs are on the bus?


Answer is 10990 legs

§ Let's say the whole situation simply :
- There are 7 girls.
- Each girl has 7 backpack
- Each backpack has 7 big cats
- Each big cat has 7 little small cats.
§ Question: How many legs are there in the bus?
§ Let's focus on each part of the question systematically, write down on a piece of paper if you have to, following my steps of chains.

1. Focus on the first girl first:
A B C D E F G
Girl A has 7 backpacks

2. Now focus on first backpack A1 :
A1 A2 A3 A4 A5 A6 A7
Backpack A1 has 7 big cats

3. Now focus on first big cat :
1 2 3 4 5 6 7

Ø Each big cats have 7 small cats (that's the end of the focus)
Systematically, 7 small cats has 28 legs (7 * 4) combined with the big cat that owns this 7 small cats.

Let's call this the "cat chain", so cat chain 1 has 32 legs altogether.
Ø So since there are 7 big cats
7 * 32 = 224 legs

Ø Therefore each backpack has 224 legs

Ø Finally, each girl has 7 * 224 = 1568 legs.

Lastly, since there are 7 girls, A to G, there are 7 * 1568 legs (per girl) = 10976 legs.

Now, since each girl also has 2 legs each;
SO, (7 * 2) + 10976 = 10990 legs altogether

Note: Disregarding bus driver, buses and etc…Only focus on the girl and their backpacks!

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