This collection of challenges can be used with students to test their skill at working systematically.
problem
Favourite
Reach 100
Age
7 to 11
Challenge level
Choose four different digits from 1-9 and put one in each box so that the resulting four two-digit numbers add to a total of 100.
problem
Favourite
Sticky Numbers
Age
11 to 14
Challenge level
Can you arrange the numbers 1 to 17 in a row so that each adjacent pair adds up to a square number?
problem
ACE, TWO, THREE...
Age
11 to 14
Challenge level
Can you picture how to order the cards to reproduce Charlie's card trick for yourself?
problem
Favourite
Two and Two
Age
7 to 16
Challenge level
How many solutions can you find to this sum? Each of the different letters stands for a different number.
problem
Favourite
Product Sudoku
Age
11 to 16
Challenge level
The clues for this Sudoku are the product of the numbers in adjacent squares.
problem
Pair Sums
Age
11 to 14
Challenge level
Five numbers added together in pairs produce: 0, 2, 4, 4, 6, 8, 9, 11, 13, 15 What are the five numbers?