# Brainteasers

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

At the table

There are six people in the Green family: two parents, two girls and two boys.

There are six chair around their kitchen table.

The two girls never sit opposite to or next to each other.

The two boys never sit opposite to or next to each other.

The two parents never sit opposite to or next to each other.

How do the Green family sit at their kitchen table?

Domino spots

The standard set of dominoes used in Europe consists of a double-6 set of 28 dominoes with all possible combinations of numbers from 0 to 6.

A double-3 set of 10 dominoes has all possible combinations of numbers from 0 to 3.

Work out a rule for the total number of spots in any set of dominoes.

Domino spots The total number of spots in a double-n set of dominoes is (n+1)2(n+2) The total number of spots on a double-5 set is: (7x5) + (7x4) + (7x3) + (7x2) + (7x17x (5+4+3+2+17 x (the sum of the numbers 1 to 5). The total number of spots on a double-n set is: (n+2) x (the sum of the numbers 1 to n(n+2) x n(n2+1)= n(n+1)(2n+2)

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