21 brain games guaranteed to boost your brain power

Your brain isn’t a muscle – in fact, it’s mostly fat – but the right kind of mental exercise can help keep it in shape. These puzzles are designed to give your problem-solving, reasoning, and concentration skills a workout. And they come in varying degrees of difficulty, so pace yourself!

How many times does the digit 5 occur in the numbers from 1 to 100?

Twenty times. The digit 5 appears 10 times as a last digit (5, 15, 25 … 95) and 10 times as a first digit (50, 51, 52 … 59).

The grid contains matches of different sizes, any of which may be completely unburned, partially burned, or completely burned. Matches burn from the head (the red end) to the tail without skipping segments. The numbers outside the grid indicate the number of burned segments in the corresponding row or column. Can you shade in the burned segments to ‘match’ the numbers?

Sophie and Caroline made arrangements to meet at a café at 2pm. Sophie thinks her watch is 25 minutes fast, although it is actually 10 minutes slow. Caroline thinks her watch is 10 minutes slow, while it is actually 5 minutes fast. What will happen if they both aim to arrive exactly on time?

Sophie will be 35 minutes late. Caroline will arrive at 1.45pm, 15 minutes ahead of time.

Space dust has landed on Earth, carrying with it seeds for exotic new alien flowers. One of them still lacks a name. If the xenobotanists follow the same rules they used to create the other terms, what should they call the last flower?

Cosmofilium jupibristo. The first half of the top term tells the colour of the flower’s centre; the last half is the petal colour. The first half of the bottom term tells the shape of the flower’s centre; the last half is the shape of the petals.

Test your vocabulary with this obscure word quizz.

Place the words listed 
in the crossword grid.