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Algebra

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?

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October 05, 2013 7:51AM

As a riddle, the answer is zero legs on the bus since the bus has wheels instead of legs.

But as a maths problem; It's not a tricked question -- just a straightforward maths problem

Confirmed 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!

Or

There are 7*7 = 49 bags and there are 7 + 7*7 = 56 cats in each bag, meaning there are 56*4 = 224 legs in each bag. So including the 7 children that have 2 legs each, there are 7*2 + 49(224) = 10990 legs in total.