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Pizza brainteaser!

By , 1 November 2012

Pizza delivery man holding a pizza

“Would you like a slice of my tasty pizza? You’ll have to solve this puzzle first!”

Mario has a whole pizza that hasn’t been cut. He cuts the pizza in half, and then cuts each of those pieces in half to make four pieces. He then cuts all of those slices in half, and then those in half and so on.

How many times does he have to cut all slices in half to get more than one hundred pieces?

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  1. It need to be cut seven times

    You basically double the number, so you get 1,2,4,8,16,32,64,128… Etc.

    The commas indicate a cut

    1. Well done – your answer looks good to me!

      Here’s a follow-up question:

      Unfortunately, Mari doesn’t have any fancy pizza cutting gizmos, and it takes him one cut to cut one piece of pizza in half. How many cuts does it take for Mario to have 100 pieces of pizza?

      1. (This is my thought process)


        First 1… Then 2…. Then 3…. Then 4….

        Continue the pattern, would probably be 99…. Because you need one cut for two slices, two cuts for three slices, three cuts for four slices, etc. So that means 99 cuts for 100 slices

        My answer: Mari will need to cut the pizza ninety-nine times to get one hundred slices of pizza

        Thanks for the questions! I need to use my brain during the holidays! Oh, and my mum works at CSIRO too, in the Parkville “campus”


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