This is part of our collection of Short Problems.
You may also be interested in our longer problems on Exploring and Noticing.
problem
Royal Arm Wrestling
How many arm-wrestles will there be in the royal arm wrestling championship?
problem
Take a Leaf
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?
problem
Halloween Day
One year there were exactly four Tuesdays and four Fridays in October. On what day of the week was Halloween.
problem
How many Rectangles?
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?
problem
Knockdown
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?
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?
problem
Out of Sync
Albert Einstein could see two clocks which were out of sync. For what fraction of the day did they show the same time?
problem
Too Close to Call
Weekly Problem 24 - 2012
Can you put these very close fractions into order?
Can you put these very close fractions into order?
problem
Almost Constant Digits
How many 10-digit numbers containing only 1s, 2s and 3s can you write?
problem
Newspaper Sheets
From only the page numbers on one sheet of newspaper, can you work out how many sheets there are altogether?
problem
Collatz-ish
A sequence is generated using these rules. For which values of n is the nth term equal to n?
problem
Back in Time
How many times a day does a 24 hour digital clock look the same when reflected in a horizontal line?
problem
Oldest and Youngest
Edith had 9 children at 15 month intervals. If the oldest is now six times as old as the youngest, how old is her youngest child?
problem
12345
Repeat a pattern of numbers to form a larger number. Can you find the sum of all the digits?
problem
Day of the Triffids
Jasmine buys three different types of plant. How many triffids did she buy?