Solve this Sudoku puzzle whose clues are in the form of sums of the
numbers which should appear in diagonal opposite cells.
A Sudoku with clues given as sums of entries.
We're excited about this new program for drawing beautiful mathematical designs. Can you work out how we made our first few pictures and, even better, share your most elegant solutions with us?
Place the numbers 1 to 10 in the circles so that each number is the
difference between the two numbers just below it.
If these elves wear a different outfit every day for as many days
as possible, how many days can their fun last?
A magician took a suit of thirteen cards and held them in his hand
face down. Every card he revealed had the same value as the one he
had just finished spelling. How did this work?
What happens when you try and fit the triomino pieces into these
A particular technique for solving Sudoku puzzles, known as "naked pair", is explained in this easy-to-read article.
Use the clues to colour each square.
In this problem it is not the squares that jump, you do the jumping! The idea is to go round the track in as few jumps as possible.
A little mouse called Delia lives in a hole in the bottom of a
tree.....How many days will it be before Delia has to take the same
Have a go at this well-known challenge. Can you swap the frogs and toads in as few slides and jumps as possible?
Can you work out how to balance this equaliser? You can put more
than one weight on a hook.
How many models can you find which obey these rules?
Place the numbers 1 to 6 in the circles so that each number is the
difference between the two numbers just below it.
Investigate the smallest number of moves it takes to turn these
mats upside-down if you can only turn exactly three at a time.
A game for 2 people. Take turns placing a counter on the star. You
win when you have completed a line of 3 in your colour.
Can you cover the camel with these pieces?
Use the interactivity to find all the different right-angled
triangles you can make by just moving one corner of the starting
Can you put the numbers from 1 to 15 on the circles so that no
consecutive numbers lie anywhere along a continuous straight line?
This problem is based on a code using two different prime numbers
less than 10. You'll need to multiply them together and shift the
alphabet forwards by the result. Can you decipher the code?
How many triangles can you make using sticks that are 3cm, 4cm and 5cm long?
You have 4 red and 5 blue counters. How many ways can they be
placed on a 3 by 3 grid so that all the rows columns and diagonals
have an even number of red counters?
Hover your mouse over the counters to see which ones will be
removed. Click to remover them. The winner is the last one to
remove a counter. How you can make sure you win?
Use the clues to work out which cities Mohamed, Sheng, Tanya and
Bharat live in.
Arrange the digits 1, 1, 2, 2, 3 and 3 so that between the two 1's
there is one digit, between the two 2's there are two digits, and
between the two 3's there are three digits.
A tetromino is made up of four squares joined edge to edge. Can
this tetromino, together with 15 copies of itself, be used to cover
an eight by eight chessboard?
Exactly 195 digits have been used to number the pages in a book.
How many pages does the book have?
Try out the lottery that is played in a far-away land. What is the
chance of winning?
Use the information to describe these marbles. What colours must be
on marbles that sparkle when rolling but are dark inside?
Place the numbers 1 to 8 in the circles so that no consecutive
numbers are joined by a line.
Can you find all the different triangles on these peg boards, and
find their angles?
Use the interactivity to help get a feel for this problem and to find out all the possible ways the balls could land.
Try this matching game which will help you recognise different ways of saying the same time interval.
This article for teachers describes several games, found on the
site, all of which have a related structure that can be used to
develop the skills of strategic planning.
How many trains can you make which are the same length as Matt's,
using rods that are identical?
Can you find all the different ways of lining up these Cuisenaire
Here are some rods that are different colours. How could I make a dark green rod using yellow and white rods?
Make a pair of cubes that can be moved to show all the days of the
month from the 1st to the 31st.
In this game for two players, you throw two dice and find the product. How many shapes can you draw on the grid which have that area or perimeter?
How many different triangles can you make on a circular pegboard
that has nine pegs?
How many different rhythms can you make by putting two drums on the
How many different ways can you find to join three equilateral
triangles together? Can you convince us that you have found them
How many different triangles can you draw on the dotty grid which each have one dot in the middle?
In this matching game, you have to decide how long different events take.
Ben and his mum are planting garlic. Use the interactivity to help
you find out how many cloves of garlic they might have had.
If you hang two weights on one side of this balance, in how many
different ways can you hang three weights on the other side for it
to be balanced?
Place six toy ladybirds into the box so that there are two
ladybirds in every column and every row.
In how many ways could Mrs Beeswax put ten coins into her three
puddings so that each pudding ended up with at least two coins?
Arrange the four number cards on the grid, according to the rules,
to make a diagonal, vertical or horizontal line.