Person: AlBaghdadi, Abu Mansur ibn Tahir
AlBaghdadi was an Islamic mathematician who wrote about different systems of arithmetic in a work of great importance in the history of mathematics.
Mathematical Profile (Excerpt):
 His full name is Abu Mansur Abr alQahir ibn Tahir ibn Muhammad ibn Abdallah alTamini alShaffi alBaghdadi.
 We can deduce from alBaghdadi's last two names that he was descended from the Bani Tamim tribe, one of the Sharif tribes of ancient Arabia, and that he belonged to the Madhhab Shafi'i school of religious law.
 We have a few details of alBaghdadi's life.
 When riots broke out in Nishapur, alBaghdadi decided that he required a more peaceful place to continue his life as an academic so he moved to Asfirayin.
 This town was quieter and alBaghdadi was able to teach and study in more peaceful surroundings.
 In Asfirayin, alBaghdadi taught for many years in the mosque.
 This treatise, alTakmila fi'lHisab, is a work in which alBaghdadi considers different systems of arithmetic.
 In this work alBaghdadi stresses the benefits of each of the systems but seems to favour the Indian numerals.
 This becomes clear from the references to the lost work by alBaghdadi.
 AlBaghdadi gives an interesting discussion of abundant numbers, deficient numbers, perfect numbers and equivalent numbers.
 AlBaghdadi gives some elementary results and then states that 945 is the smallest odd abundant number, a result usually attributed to Bachet in the early 17th century.
 However, alBaghdadi knew that certain claims made by Nicomachus were false.
 Next alBaghdadi goes on to define equivalent numbers, and appears to be the first to study them.
 The results that alBaghdadi gives on amicable numbers are only a slight variations on results given earlier by Thabit ibn Qurra.
Born about 980, Baghdad, Iraq. Died 1037.
View full biography at MacTutor
Tags relevant for this person:
Ancient Arab, Origin Iraq, Special Numbers And Numerals
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References
Adapted from other CC BYSA 4.0 Sources:
 Oâ€™Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive