Self-revealing hints are available below. I recommend looking at them one at a time, and only in case of frustration. Do not spoil the satisfaction of having the “aha-moment”! **Before looking at the hints, check out Tips for Solving.**

You may prefer to request a personalized hint by email. In that case, please mention which puzzle you are working on, and what you have tried so far. If you’d like only a small nudge, you may try to ask only a few yes/no questions.

##### Puzzle 1.0 (Access Password)

## Hint 1 (click to display)

y-1 = x.

## Hint 2 (click to display)

Use alphabetical ranking (g=7,…) and compute the differences. The password is a four-letter English word.

##### Puzzle 1.1: Virtual Confusion

## Hint 1 (click to display)

You should be able to identify most, if not all, participants of this meeting, maybe with the help of the internet.

## Hint 2 (click to display)

The transition to remote meeting left each participant of the Zoom meeting somewhat *mixed-up*.

## Hint 3 (click to display)

Use the *extra*ordinary feature of each participant to spell out the answer.

##### Puzzle 1.2: Mathematical Encounters

## Hint 1 (click to display)

Each definition in the first section corresponds to a mathematical term. The circles give the word lengths. They are in alphabetical order.

## Hint 2 (click to display)

The second section contains mathematical examples of the same terms.

## Hint 3 (click to display)

Read the matrix to know what to do at the end. You should select one entry per row and column, and obtain a link.

##### Puzzle 1.3: International Party

## Hint 1 (small nudge)

Hint — Pista — Indice — Hinweis — Indizio: Multilingual teams have an advantage when solving this puzzle. The others will have to use a few dictionaries.

## Hint 2 (another small nudge)

Some words are especially *important* in the announcement.

## Hint 3 (more explicit hint)

Each line represents the same things in a different language. The languages can be determined from the title of the blackboard. What represents each line is hinted at by the italicized words in the introduction: *counting, number, language, the end, more than ten*.

## Hint 4 (much more explicit hint)

Write down the numbers from 10 in English (ten, eleven, …), what do you notice about the endings? What if you do the same in the other languages?

## Hint 5 (on how to extract the answer)

The white rectangles hide the same type of information as the other elements of the sequences. Notice that the numbers in these rectangles are not always in the same position.

##### Puzzle 1.4 (Metapuzzle): Magical Trees

## Hint 1 (click to display)

This is a *metapuzzle*. You need the three previous answers to solve it.

## Hint 2 (click to display)

Fill the binary trees by extracting the correct letters from the answer words. You should get binary operations for the three red symbols, and some kind of numbers for the leaves. Then do the computations.

## Hint 3 (click to display)

Which (unary) operation could the red square represent? Where is it located? The final answer can be read in the purple rectangles.