This Sudoku, based on differences. Using the one clue number can you find the solution?
Can you order pictures of the development of a frog from frogspawn
and of a bean seed growing into a plant?
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?
Can you use the information to find out which cards I have used?
Place the numbers 1 to 8 in the circles so that no consecutive
numbers are joined by a line.
Try out the lottery that is played in a far-away land. What is the
chance of winning?
Rather than using the numbers 1-9, this sudoku uses the nine
different letters used to make the words "Advent Calendar".
I was in my car when I noticed a line of four cars on the lane next
to me with number plates starting and ending with J, K, L and M.
What order were they in?
A man has 5 coins in his pocket. Given the clues, can you work out
what the coins are?
This challenging activity involves finding different ways to distribute fifteen items among four sets, when the sets must include three, four, five and six items.
If these elves wear a different outfit every day for as many days
as possible, how many days can their fun last?
This challenge extends the Plants investigation so now four or more children are involved.
A particular technique for solving Sudoku puzzles, known as "naked pair", is explained in this easy-to-read article.
Use the clues to work out which cities Mohamed, Sheng, Tanya and
Bharat live in.
Move your counters through this snake of cards and see how far you
can go. Are you surprised by where you end up?
Four small numbers give the clue to the contents of the four
Use the differences to find the solution to this Sudoku.
Seven friends went to a fun fair with lots of scary rides. They
decided to pair up for rides until each friend had ridden once with
each of the others. What was the total number rides?
A package contains a set of resources designed to develop
students’ mathematical thinking. This package places a
particular emphasis on “being systematic” and is
designed to meet. . . .
An extra constraint means this Sudoku requires you to think in
diagonals as well as horizontal and vertical lines and boxes of
Exactly 195 digits have been used to number the pages in a book.
How many pages does the book have?
A few extra challenges set by some young NRICH members.
Can you find which shapes you need to put into the grid to make the
totals at the end of each row and the bottom of each column?
Solve this Sudoku puzzle whose clues are in the form of sums of the
numbers which should appear in diagonal opposite cells.
Bellringers have a special way to write down the patterns they
ring. Learn about these patterns and draw some of your own.
In a square in which the houses are evenly spaced, numbers 3 and 10
are opposite each other. What is the smallest and what is the
largest possible number of houses in the square?
Can you arrange the numbers 1 to 17 in a row so that each adjacent
pair adds up to a square number?
Four friends must cross a bridge. How can they all cross it in just
You have been given nine weights, one of which is slightly heavier
than the rest. Can you work out which weight is heavier in just two
weighings of the balance?
My local DIY shop calculates the price of its windows according to the area of glass and the length of frame used. Can you work out how they arrived at these prices?
Roll two red dice and a green dice. Add the two numbers on the red dice and take away the number on the green. What are all the different possibilities that could come up?
Make a pair of cubes that can be moved to show all the days of the
month from the 1st to the 31st.
When you throw two regular, six-faced dice you have more chance of getting one particular result than any other. What result would that be? Why is this?
Sweets are given out to party-goers in a particular way. Investigate the total number of sweets received by people sitting in different positions.
Can you use your powers of logic and deduction to work out the missing information in these sporty situations?
Follow the clues to find the mystery number.
What happens when you add three numbers together? Will your answer be odd or even? How do you know?
A Sudoku with clues as ratios.
Zumf makes spectacles for the residents of the planet Zargon, who
have either 3 eyes or 4 eyes. How many lenses will Zumf need to
make all the different orders for 9 families?
This pair of linked Sudokus matches letters with numbers and hides a seasonal greeting. Can you find it?
Are all the possible combinations of two shapes included in this
set of 27 cards? How do you know?
A Sudoku with a twist.
What do the digits in the number fifteen add up to? How many other
numbers have digits with the same total but no zeros?
60 pieces and a challenge. What can you make and how many of the
pieces can you use creating skeleton polyhedra?
How can you put five cereal packets together to make different
shapes if you must put them face-to-face?
Tim had nine cards each with a different number from 1 to 9 on it.
How could he have put them into three piles so that the total in
each pile was 15?
Tim's class collected data about all their pets. Can you put the
animal names under each column in the block graph using the
Arrange eight of the numbers between 1 and 9 in the Polo Square
below so that each side adds to the same total.
Alice and Brian are snails who live on a wall and can only travel
along the cracks. Alice wants to go to see Brian. How far is the
shortest route along the cracks? Is there more than one way to go?
This practical challenge invites you to investigate the different
squares you can make on a square geoboard or pegboard.