Mary wrote a number on each face  of a cube. Then, for each vertex, she added the numbers on the three faces sharing that vertex ( for example, for vertex B she added the numbers on faces BCDA, BAEF and BFGC ). The numbers computed by Mary for vertices C, D and E were 14, 16 and 24, respectively. What number did she compute for vertex F ?

A train has 12 coaches. Each coach has the same number of compartments. Mike is travelling in the third coach and in the 18^th compartment from the engine. Jane sat in the 7^th coach in the 50^th compartment from the engine. How many compartments are there in each coach ?

In how many ways can you place the three kangaroos in three different cells, out of the seven cells belows, so that not two kangaroos are neighbours ?

Four points lie on a line. The distances between them are, in increasing order:

2, 3, k, 11, 12, 14. What is the value of k ?

Basil used small cubes with side 1 to construct a cube with side 4. After that, he painted 3 faces of the big cube red and the other 3 faces blue. After he finished, there was no small cube with 3 red faces. How many small cubes have botth red and blue faces ?

Eugenie folded a round sheet of paper in half, three times, along the dotted lines, as shown in a, b and c below.

Then she cut the folded paper along the marked line, parallel to the folding line, as shown to the right.

Finally, Eugenie unfolded the paper. What shape did she obtain ?

Which of the weights are going upwards when the lower left wheel is turned clockwise as indicated ?

We want to insert the numbers 1, 2, 3, 4, 5, 6, 8 and 9 into the empty boxes below so that the sum of the numbers in each row, in each column, and in both the diagonals adds up to the same amount. What is the sum of the four numbers in the shaded boxes ?

Two three – digit numbers have all their six digits distinct. The first digit of the second number is twice the last digit of the first number. What is the smallest possible sum of two such numbers ?

A little Kangaroo is playing with his calculator allowing only operations on integers with an integer result. He starts with the number 12. He multiplies or divides the number by 2 or 3 ( if possible ) 60 times in a row. Which of the following results cannot be obtained ?

A big cube was built from 8 identical small cubes, some black ones and some white ones. Five faces of the big cube, seen from some viewpoint, are:

What does the sixth face of the big cube look like ?

Clara wants to construct a big triangle using identical small triangular tiles. She has already put some tiles together as shown in the picture.

What is the minimum number of additional tiles required to complete a triangle ?

Luigi started a small restaurant. His friend Giacomo gave him several square tables and chairs. If he uses all the tables as single tables with 4 chairs each, he would need 6 more chairs. If he uses all the tables as double tables with 6 chairs each, he would have 4 chairs left over. How many tables did Luigi get from Giacomo ?

Richard is writing down all the numbers with the following properties:

- the first digit is 1

- each of the following digits is at least as big as the one before it

- the sum of the digits is 5

How many numbers will he write ?