# African calculators and tools for perpetual Gregorian calendar

This gallery aims at promoting African invention and innovation in the field of Gregorian calendar; particularly the contribution of Malam Sidi IYE (born in 1928 in Niger) and his grandson Dr Ibrahim SIDI ZAKARI. The pictures include:

- A vertical calculator for dates searching
- A circular calculator for dates searching
- A tutorial for the calculators (vertical and circular)
- An ancient calendar (sample) with years classification
- A perpetual calendar covering 600 years period (from 1701 to 2300) with years classification and tutorial
- A computer Keyboard including a two steps mathematical algorithm for dates searching

The common elements of the pictures can be classified as follows:

- Mathematics: all of the six pictures are based on algorithms for the arithmetic of positive integers, symetry and periodicity.
- Languages: French+Arabic (for the first five (5) pictures) and English for the last one.
- Authors: The first five (5) pictures have been created by Malam Sidi IYE (from early 1950 to 2014), the last picture (computer keyboard) has been created by Dr Ibrahim SIDI ZAKARI in 2016, when participating (as Next Einstein Forum’s Ambassador) to the Challenge from Invention to Innovation (NEF Global Gathering, Dakar, Senegal, 2016).
- Aesthetics: color code and manuscript design have been integrated in most of the pictures.
- Originality: As far as we know, these pictures are unique in the world.

## Vertical calculator for dates searching

This vertical calculator for dates searching was invented by malam sidi IYE. Computations are made from top to bottom and bottom to top, right to left and left to right.

## Circular calculator for dates searching

This circular calculator for dates searching was invented by malam sidi IYE. Computations are made in a circular manner.

## Tutorial for the calculator

This tutorial is dedicated to the calculators (vertical and circular) of Malam Sidi IYE.

## Sample of ancient calendar manuscript

This is one of the 14 calendars sample created by Malam Sidi IYE.

## Perpetual Gregorian calendar covering period 1701 to 2300

Gregorian calendar covering period 1701 to 2300 and published by the Republic of Niger (in 2013-2014) in recognition of the great achievement and contribution of Malam Sidi IYE.

## Tabtakey: The innovative computer keyboard for dates searching.

Tabtakey is an innovative computer keyboard integrating a two steps mathematical algorithm for Gregorian calendar. It can be used for promoting lifelong learning (alphabetization,arithmetics,probability,statistics,algorithmic,history,programming,…).As a standalone device, it is adpated for rural and urban areas. Physical and virtual(software or mobile app) options can be implemented.