Suit Sequence
Age 11 to 14 Short
Challenge Level
A pattern repeats every six symbols. What are the 100th and 101st symbols?
Royal Arm Wrestling
Age 11 to 14 Short
Challenge Level
How many arm-wrestles will there be in the royal arm wrestling championship?
Take a Leaf
Age 11 to 14 Short
Challenge Level
An examination paper is made from five pieces of paper. What is the sum of the other page numbers that appear on the same sheet as page 5?
Out of Sync
Age 11 to 14 Short
Challenge Level
Albert Einstein could see two clocks which were out of sync. For what fraction of the day did they show the same time?
Halloween Day
Age 11 to 14 Short
Challenge Level
One year there were exactly four Tuesdays and four Fridays in October. On what day of the week was Halloween.
How Many Rectangles?
Age 11 to 14 Short
Challenge Level
By drawing 5 horizontal and four vertical lines, one can form 12 rectangles. What is the greatest number of rectangles that can be formed by drawing 15 lines?
Knockdown
Age 11 to 14 Short
Challenge Level
Weekly Problem 51 - 2016
Pegs numbered 1 to 50 are placed in a row. Alternate pegs are knocked down, and this process is repeated. What is the number of the last peg to be knocked down?
Too Close to Call
Age 11 to 14 Short
Challenge Level
Weekly Problem 24 - 2012
Can you put these very close fractions into order?
Almost Constant Digits
Age 11 to 14 Short
Challenge Level
How many 10-digit numbers containing only 1s, 2s and 3s can you write?
Newspaper Sheets
Age 14 to 16 Short
Challenge Level
From only the page numbers on one sheet of newspaper, can you work out how many sheets there are altogether?
Collatz-ish
Age 14 to 16 Short
Challenge Level
A sequence is generated using these rules. For which values of n is the nth term equal to n?
12345
Age 14 to 16 Short
Challenge Level
Repeat a pattern of numbers to form a larger number. Can you find the sum of all the digits?
Back in Time
Age 14 to 16 Short
Challenge Level
How many times a day does a 24 hour digital clock look the same when reflected in a horizontal line?
NRICH is part of the family of activities in the Millennium Mathematics Project.