Reverse Ages
Age 11 to 14 Short Challenge Level:
When is the next time that Brian's age will be the reverse of his father's age?
Central Sum
Age 11 to 14 Short Challenge Level:
Can you find numbers between 100 and 999 that have a middle digit equal to the sum of the other two digits?
Negative Dice
Age 11 to 14 Short Challenge Level:
If the odd numbers on two dice are made negative, which of the totals cannot be achieved?
Rough Rectangle
Age 11 to 14 Short Challenge Level:
What is the smallest possible area that this rectangle could have?
Debt Recovery
Age 11 to 14 Short Challenge Level:
Tony and Tina can't work out which of them owes what to the other. Can you?
Loose Change
Age 11 to 14 Short Challenge Level:
In how many ways can you give change for a ten pence piece?
Mathematical Ages
Age 11 to 14 Short Challenge Level:
Arrange these three famous mathematicians in order with the shortest-lived first.
Quiz Questions
Age 11 to 14 Short Challenge Level:
Jack does a 20-question quiz. How many questions didn't he attempt?
Mini Kakuro
Age 11 to 14 Short Challenge Level:
The sum of each column and row in this grid give the totals as shown. What number goes in the starred square?
Highs and Lows
Age 11 to 14 Short Challenge Level:
What were the maximum and minimum temperatures recorded in my max/min thermometer?
Tick Tock
Age 11 to 14 Short Challenge Level:
Tick's watch is slow and Tock's watch is fast. How long is it before their watches differ by an hour?
Double with 1 to 9
Age 11 to 14 Short Challenge Level:
Can you find a number and its double using the digits $1$ to $9$ only once each?
Paying the Bill
Age 11 to 14 Short Challenge Level:
Gill and I went out to lunch. We agreed to split the total cost equally. How much did I owe Gill?
Digital Book
Age 11 to 14 Short Challenge Level:
If it takes 852 digits to number all the pages of a book, what is the number of the last page?
Missing 9s
Age 11 to 14 Short Challenge Level:
Sara makes a list of the whole numbers that do not contain any 9s. What is the 300th number on her list?
Even Squares
Age 11 to 14 Short Challenge Level:
Can you find squares within a number grid whose entries add up to an even total?
Digit Sum Puzzle
Age 11 to 14 Short Challenge Level:
Let N be the smallest positive integer whose digits add up to 2015. What is the sum of the digits of N+1?
Equal Length Powers
Age 14 to 16 Short Challenge Level:
How many positive integers $n$ exist for which $n^2$ has the same number of digits as $n^3$?
Alberta's Age
Age 14 to 16 Short Challenge Level:
Alberta won't reveal her age. Can you work it out from these clues?
Repeat Product
Age 14 to 16 Short Challenge Level:
Can you work out the value of P+Q+R in the multiplication shown?
Sum Up
Age 14 to 16 Short Challenge Level:
David listed ten consecutive numbers and removed one of them. Which number did he remove?
Pros and Cons
Age 14 to 16 Short Challenge Level:
If p is a positive integer and q is a negative integer, which of these expressions is the greatest?
How Many Gorillas?
Age 14 to 16 Short Challenge Level:
If the numbers in this news article have been estimated, then what is the largest number of gorillas that there could have been 10 years ago?
Number Crunch
Age 14 to 16 Short Challenge Level:
Create 24 numbers from four digits. Why is 101 always a factor of their sum?
Digital Counter
Age 14 to 16 Short Challenge Level:
When the numbers from 1 to 1000 are written on a blackboard, which digit appears the most number of times?
Digit Sum
Age 14 to 16 Short Challenge Level:
What is the sum of all the digits in all the integers from one to one million?
NRICH is part of the family of activities in the Millennium Mathematics Project.