Skip to main content

Brainteasers

Puzzles to test mathematical skills, set by Anita Straker. Solutions below More brainteasers on www.tes.co.ukteacherbrainteasers

Know your alphabet

Use each of the letters A, B, C, D and E.

Write one letter in every circle.

Letters joined by lines must not be next to each other in the alphabet.

Now try this one.

Perimeters

This shape has a perimeter of 12 units.

Add more squares to the shape so that they touch edge to edge.

What is the minimum number of squares that must be added to make a perimeter of 18?

What is the maximum number of squares that can be added to make a perimeter of 18?

SOLUTIONS

Know your alphabet (age 5 to 8) other solutions are possible.

Answers

Perimeters (age 10 to 14) Adding one square to a shape made from squares touching edge to edge could change its perimeter by +2, 0, - 2 or - 4 units, depending on where the extra square is positioned and the arrangement of squares in the original shape. At least 3 squares must be added to make a perimeter of 18. For example: the maximum number of squares that can be added to make a perimeter of 18 is 14, positioned so that the whole shape forms a 4 by 5 rectangle.

Log in or register for FREE to continue reading.

It only takes a moment and you'll get access to more news, plus courses, jobs and teaching resources tailored to you