Working systematically

problem

Multiplication Table Puzzle

Age

11 to 14

Challenge level

1 out of 3

In the multiplication table on the right, only some of the numbers have been given. What is the value of A+B+C+D+E?
problem

Master Minding

Age

11 to 14

Challenge level

2 out of 3

Your partner chooses two beads and places them side by side behind a screen. What is the minimum number of guesses you would need to be sure of guessing the two beads and their positions?
problem

Pattern of Islands

Age

11 to 14

Challenge level

2 out of 3

In how many distinct ways can six islands be joined by bridges so that each island can be reached from every other island...
problem

So Many Sums

Age

11 to 14

Challenge level

2 out of 3

In this addition each letter stands for a different digit, with S standing for 3. What is the value of YxO?
problem

Blockupied

Age

11 to 14

Challenge level

2 out of 3

A 1×2×3 block is placed on an 8×8 board and rolled several times.... How many squares has it occupied altogether?
problem

Even Squares

Age

11 to 14

Challenge level

2 out of 3

Can you find squares within a number grid whose entries add up to an even total?
problem

Double With 1 to 9

Age

11 to 14

Challenge level

2 out of 3

Can you find a number and its double using the digits $1$ to $9$ only once each?
problem

Rolling Along the Trail

Age

11 to 14

Challenge level

2 out of 3

What could be the scores from five throws of this dice?
problem

The Square of My Age

Age

11 to 14

Challenge level

2 out of 3

Lauren and Thomas tell their ages in terms of sums of squares. Can you work out how old they really are?
problem

Staircase Sum

Age

11 to 14

Challenge level

2 out of 3

The digits 1-9 have been written in the squares so that each row and column sums to 13. What is the value of n?