Problem No. 7. Coins on a table

There are 7 coins laid on a table with the heads up, and 30 coins laid with the tails up. Each coin has a head side and a tail side. How can you split the coins in two piles, with your eyes closed, so that the piles have the same number of coins with the tails up?

Teacher tip

Use logic puzzles at your classes to increase the motivation and to exercise the flexibility in mathematical thinking.

Problem No. 6. Clock hands revisited

How many times in a day the clock hands will form the same angle as the angle at 7.30?

Student tip

For a hint use Problem No. 3.

Problem No. 5. Missing numbers

Here is a 5 x 5 table filed with numbers according to some rule. What are the missing numbers?

Parent tip

Exploring patterns with your children can be a fun way to spend some quality time together.

Problem No. 4. Airplane fly

The travel by plane from Paris,France to New York City, USA, takes about 8 hours. If a passenger starts his journey from Paris at 7.30 pm local time, when is he supposed to arrive at New York City, local time?

Teacher tip

Problems with an extra-mathematical knowledge are suitable to demonstrate the application of math and its interdisciplinary character. Here, the students should be familiar with or should first learn about time zones.

Problem No. 3. Clock hands

It is 7.30 now. How much time will it pass until the clock hands form the same angle again?

Student tip

Suppose that minute and hour hands move at a constant velocity each.