> ## Content Index
> Fetch the complete content index at: https://www.protein.xyz/llms.txt
> Use this file to discover other available public pages before exploring further.

# Knock Knock
- URL: https://www.protein.xyz/knock-knock/
- Published: 2013-05-06T16:27:00.000Z
- Updated: 2025-05-28T11:01:26.000Z
- Description: A super minimalist redesign of the classic calculator that uses audio stimulation instead of a screen.
- Author: Protein
- Tags: Seeds, Art & Design, #protein, #Import 2024-06-11 13:21, #author-change-2025-05-28

![](https://storage.ghost.io/c/fc/71/fc716215-5729-441a-bd07-e2b50bc413b1/content/images/S3/protein/9250/d28dbe7c-9ffe-4b0e-9a6a-fe8d7e0b7cfb.jpeg)

[Khalil Klouche](http://www.klouche.com/?ref=protein.xyz), a masters student at Haute Ecole d’Art et de Design (HEAD) Geneva, has designed a playful and interactive calculator for kids formed of a wooden block and the four key arithmetic symbols: add, subtract, multiply, divide.  
The gadget, [Knock Knock](http://www.klouche.com/knock-knock/?ref=protein.xyz), has been created using an Arduino board, contact microphones and solenoids, and was first showcased at the exhibition ‘Touch!’ for [Museum of Design and Contemporary Art](http://www.mudac.ch/?ref=protein.xyz). To calculate a sum, the user must knock the number corresponding to the sign – so to multiply by two, you must knock twice on the ‘X’ symbol. The total of the sum is then ‘answered’ by the calculator with knocking sounds via the speaker.  
It’s a simple, touch-activated way of stimulating a number of the senses, and an innovative redesign of a classic piece of technology.

![](https://storage.ghost.io/c/fc/71/fc716215-5729-441a-bd07-e2b50bc413b1/content/images/S3/protein/9250/8800c6dc-c2e5-48e6-9316-a140d13f31d5.jpeg)

![](https://storage.ghost.io/c/fc/71/fc716215-5729-441a-bd07-e2b50bc413b1/content/images/S3/protein/9250/b17a6e67-d249-48ff-80d2-e40f2c48baf1.jpeg)