### 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?

### Solution 1:

To calculate the total number of legs on the bus, we need to multiply the number of each type of object by the number of legs it has, and then add up the results.

There are 7 children on the bus, and each child has 7 bags. Therefore, there are 7 x 7 = 49 bags on the bus.

Inside each bag, there are 7 big cats. Therefore, there are 49 x 7 = 343 big cats on the bus.

Each big cat has 7 small cats, so there are 343 x 7 = 2401 small cats on the bus.

__Since all cats have 4 legs each, the total number of legs on the bus is:__

7 children x 2 legs each = 14 legs

343 big cats x 4 legs each = 1372 legs

2401 small cats x 4 legs each = 9604 legs

Total number of legs on the bus = 14 + 1372 + 9604 = 10990 legs.

Therefore, there are 10990 legs on the bus.

### Solution 2:

Another way to approach the problem is to use multiplication and addition in a different order.

__Each small cat has 4 legs, so the total number of legs on all the small cats is:__

7 children x 7 bags x 7 big cats x 7 small cats x 4 legs = 7 x 7 x 7 x 7 x 4 = 9604 legs.

Similarly, each big cat has 4 legs, so the total number of legs on all the big cats is:

7 children x 7 bags x 7 big cats x 4 legs = 7 x 7 x 7 x 4 = 1372 legs.

__Finally, each child has 2 legs, so the total number of legs on all the children is:__

7 children x 2 legs = 14 legs.

__To find the total number of legs on the bus, we add up these three numbers:__

9604 legs + 1372 legs + 14 legs = 10990 legs.

Therefore, there are 10990 legs on the bus.

### Solution 3:

We can also solve this problem by breaking it down into smaller parts and then adding them up.

Each child has 7 bags, and each bag has 7 big cats, so each child has 7 x 7 = 49 big cats.

Therefore, there are 7 children x 49 big cats = 343 big cats on the bus.

Each big cat has 7 small cats, so there are 343 x 7 = 2401 small cats on the bus.

__Finally, to calculate the total number of legs on the bus, we can add up the legs of each type of object separately:__

7 children x 2 legs each = 14 legs

343 big cats x 4 legs each = 1372 legs

2401 small cats x 4 legs each = 9604 legs

Total number of legs on the bus = 14 + 1372 + 9604 = 10990 legs.

Therefore, there are 10990 legs on the bus.

### Alternative Solutions

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

The 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 on 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 the first big cat :**

1 2 3 4 5 6 7

Each big cats have 7 small cats (that's the end of the focus)

Systematically, 7 small cats have 28 legs (7 * 4) combined with the big cat that owns these 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;

So, (7 * 2) + 10976 = 10990 legs altogether

Note: Disregarding bus drivers, 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.