THE LOGIC UNDERLYING THE WRITING OF AL KHWARIZMI DIGITS OR IDEOGRAMS
By ROBERTO
DE MENEZES LYRA
Brazil
THE LOGIC UNDERLYING THE WRITING OF AL-KHWARIZMI DIGITS DURING THE MIDDLE AGES THIS IS THE WAY THE FIRST DIGIT IS WRITTEN, WITH A SINGLE ANGLE. THIS IS THE WAY THE SECOND DIGIT IS WRITTEN, WITH TWO ANGLES. THIS IS THE WAY THE THIRD DIGIT IS WRITTEN, WITH THREE ANGLES. THIS IS THE WAY THE FOURTH DIGIT IS WRITTEN, WITH FOUR ANGLES IN THE SHAPE OF A CROSS. HERE YOU SEE THE DISTINCTION BETWEEN THE FORMAT OF A CROSS AND THE FIGURE FORMED WITH THE ADDITION OF ANOTHER LINE, WHICH CAN BE SLANTED OR VERTICAL. THIS SMALL CUSTOMIZED ABACUS CAN BE USED TO COUNT IN BASE FIVE AND BASE TEN. THE BEADS OF THE LOWER DECK ARE USED TO COUNT IN BASE FIVE. THE BEADS OF THE UPPER DECK ARE USED TO COUNT IN BASE TEN. THIS BEAD HAS A VALUE OF FIVE. THIS BEAD ALSO HAS THE BASE VALUE OF FIVE, BUT A LINE SLANTING UPWARD HAS BEEN ADDED. AND THIS BEAD WITH A BASE VALUE OF FIVE HAS BEEN MODIFIED BY ADDING TWO LINES SLANTING UPWARDS. THIS BEAD HAS A VALUE OF TEN. THESE BEADS ALSO HAVE THE VALUE OF TEN, BUT THIS VALUE CAN BE DECREASED BY THE ADDITION OF A DOWNWARD SLANTING LINE. THIS BEAD REPRESENTS THE VALUE OF TEN, BUT WITH THAT VALUE DECREASED BY THE ADDITION OF TWO LINES SLANTING DOWNWARDS. THE BEADS OF THE TOP DECK ARE THE MIRROR IMAGES OF THOSE OF THE BOTTOM DECK OF THE ABACUS. THIS IS THE BEAM OF THE ABACUS. THE WRITING OF THE DIGIT FIVE IS BEGUN BY DRAWING THE BEAM OF THE ABACUS, FOLLOWED BY THE DRAWING OF THE ROD DESCENDING TO THE BEAD. THE DIGIT IS THEN TERMINATED BY PARTIALLY CIRCLING THE BEAD ITSELF, WHICH HAS THE VALUE OF FIVE. THE DIGIT SIX IS BEGUN BY CIRCLING A BEAD WITH A VALUE OF FIVE, AND ADDING AN UPWARDS SLANTING LINE. THE DIGIT OF SEVEN IS WRITTEN BY FIRST DRAWING THE BEAM OF THE ABACUS AND THEN ADDING A LINE SLANTING DOWNWARDS TO THE BEAD. INITIALLY THIS LINE FOLLOWED THE OUTLINE OF THE BEAD, BUT WITH TIME A MODIFICATION LED TO THE USE OF A LINE, TANGENTIAL TO THE BEAD, SLANTING UP TO CUT THE ORIGINAL ASCENDING LINE. THIS LATIN FORM OF THE DIGIT SEVEN WITH AN ASCENDING LINE CUTTING THE ORIGINAL DESCENDING LINE WAS SIMPLIFIED BY REMOVING THE “CUTTING” LINE. THIS IS THE WAY THE DIGIT OF TEN IS WRITTEN. IT IS WRITTEN BY CIRCLING A BEAD WITH A VALUE OF TEN. THIS IS THE WAY THE DIGIT NINE IS WRITTEN. THE FIRST STEP IS THE CIRCLING OF A BEAD WITH THE VALUE OF TEN, WHILE THE ADDITION OF A LINE SLANTING DOWNWARDS INDICATES A REDUCTION IN THAT VALUE. THIS IS THE WAY THE DIGIT EIGHT IS WRITTEN. ONE BEGINS BY CIRCLING A BEAD WITH THE VALUE OF TEN. THEN TWO DOWNWARDS SLANTING LINES ARE ADDED, REDUCING THE VALUE TO EIGHT. THE DIGIT IS COMPLETED BY JOINING THE LOWER ENDS OF THE TWO LINES. Bob Lyra - pesquisador paleografia dos algarismos / @robertolyra59 THANKS TO TRANSLATOR: Linda Gentry el-Dash https://studio.d-id.com/
