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Days and Dates
Investigate how you can work out what day of the week your birthday will be on next year, and the year after...
Prime Magic
Place the numbers 1, 2, 3,..., 9 one on each square of a 3 by 3 grid so that all the rows and columns add up to a prime number. How many different solutions can you find?
Is it Magic or Is it Maths?
Here are three 'tricks' to amaze your friends. But the really clever trick is explaining to them why these 'tricks' are maths not magic. Like all good magicians, you should practice by trying them. Can you explain how they work?
Age 11 to 14
Challenge Level
Many of you sent in excellent solutions to this problem. You tackled it using algebra, in other words using a letter to represent the number that you started with. Thank you to all pupils from Ardingly College who answered the problem in this way, and to Bronya and Caroline from Tattingstone School. Here is Alistair's solution. Alistair, who goes to Histon Junior School, has explained the algebraic steps very clearly:
If X is the number you think of, you start with X
Then when you add 1, you get X + 1
When you double it, it turns into 2X + 2
When you take away 3, it turns into 2X -1
Adding the number you first thought of makes 3X -1
When you add 7 it turns into 3X + 6
When you divide by 3 it turns into 1X + 2
Then take away the number you first thought of (X) it leaves 2.
NRICH is part of the family of activities in the Millennium Mathematics Project.