Your task: Answer the question below. Then download and open the attached Excel spreadsheet. The number of legs is the password to unlock the Excel sheet. Add your name to the spreadsheet and send it on to see who else can unlock it.

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Note: This is not a trick question. This is a real math problem so don't say that a bus has no legs. Also, there is no driver on the bus, so don't add any legs for a driver.

There are 7 girls in a bus
Each girl has 7 backpacks
In each backpack, there are 7 big cats For every big cat there are 7 little cats

Question: How many legs are there in the bus?

You have to find ways of using up to 4 numbers to match a target number exactly.

You don't have to use all the numbers - but you can use each number only once.

You can add, subtract, multiply, divide and even put them together.

Each level will vary the number of signs you can use and the choice of digits will be reduced to increase the difficulty.

Remember, there is always more than one way to reach the target number.

Notes
* You will need to have (or install) the free Shockwave Player.
* You can download the game from the website and run it as a stand-alone program

http://www.channel4learning.net/sites/puzzlemaths/make_it_count.shtml

Choose 3 large numbers and 3 small numbers, and then choose a random target. How many ways can you find to use the small numbers plus some operations and brackets to make an expression that equals the target?

And start the clock when there are only 30 seconds left.

Your calculator is missing some of its keys! Which answers can you still get?
Six levels, from easy to challenging!

The goal of this puzzle is to put three numbers inside of each circle so that they add up to 99.
http://nlvm.usu.edu/en/nav/frames_asid_269_g_3_t_1.html?open=instruction...

This virtual manipulative allows the user to visualize the product of two factors in three different ways: click on any of the options below the array to choose Grouping, Common, or Lattice.
http://nlvm.usu.edu/en/nav/frames_asid_192_g_1_t_1.html?open=instruction...

A Java applet that illustrates addition and subtraction in a variety of bases.
http://nlvm.usu.edu/en/nav/frames_asid_152_g_1_t_1.html?from=category_g_...