A distinctive Western Arabic variant of the Eastern Arabic numerals began to emerge around the 10th century in the Maghreb and Al-Andalus (sometimes called ghubar numerals, though the term is not always accepted), which are the direct ancestor of the modern Arabic numerals used throughout the world.[74] Binomial theorem: The first formulation of the binomial theorem and the table of binomial coefficient can be found in a work by Al-Karaji, quoted by Al-Samaw'al in his "al-Bahir".[75][76][77] Cauchy-Riemann Integral: Ibn al-Haytham gave a simple form of this.[5] Decimal fractions: Decimal fractions were first used by Abu'l-Hasan al-Uqlidisi in the 10th century.[78][79] Experimental scientific method: Expounded and practised by ibn al-Haytham[8][80] Fountain pen: An early historical mention of what appears to be a reservoir pen dates back to the 10th century.