Most of these mathematician apronyms are based on the biographies at

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Loose apronyms:
Perfect Apronyms OnlyAll Apronyms
ADELARDAl'Khwarizmi's Derivations Entered Latin, Also Royal Drilled. Angela Brett (Adelard of Bath was a mathematician who, among other things, translated work of Euclid and Al'Khwarizmi and taught King Henry II.)
AHMED IBN YUSUFArab-Hatched Mathematician, Expanded & Discussed Important Book. Nodoubt, Yusuf's Usual Studies Used Fractions. Angela Brett (Ahmed ibn Yusuf wrote on ratio and proportion, and expanded on/discussed book 5 of Euclid's 'Elements')
AL'BATTANIAlbategnius' Liber Bore Astronomical Tables, Trigonometric Advances & Newer Information. Angela Brett
ALBERT EINSTEINA Less-Bearded Enigmatic Researcher Tells Everyone In Natural Science That Everything's Interrelated Naturally Sean Lamb
AL'HAITAMAnalysed Lenses, Had An Important Theory About Mirrors. Angela Brett
AL'HASIBAbu Largely Helped Along Solving Irrational Bewilderment. Angela Brett
CAUCHYComplex Analysis Understood Completely... Huge Yield! Angela Brett
CH'IN CHIU SHAOComposed Haiku, Investigated Numbers & Congruences. His Interesting Understandings Stieltjes Has Afterwards Observed. Angela Brett and Dustan Dowsing
DIOPHANTUSDecided Influence On Precise, Handwritten Algebraic Notation. Thought Unpositives Superfluous. Angela Brett
EUCLID'E's Unclear... Can Lines Intersect Dually? Angela Brett, because Euclid's first postulate saying that a straight line can be drawn from any point to any point does not explicitly say that the line is unique.
EUTOCIUSEssentially Updated The Others' Calculations - Inscribed Unoriginal Summaries. Angela Brett
FERMATFamous Equation Really Made Andrew Think! Angela Brett (Andrew Wiles eventually proved Fermat's Last Theorem centuries after Fermat's death.)
GAUSSGot Answers Using Simultaneous Solutions Angela Brett, thinking of Gaussian elimination, a way of solving simultaneous equations. I didn't feel like acronymising the whole thing!
GAUSS (2)Great Arithmetic Used Solving Systems Angela Brett
GAUSS (3)Geometry's An Unexpectedly Strange Subject. Angela Brett
HENGHis Earthquake-Noticer's Great! Angela Brett
HERONHe Estimated Roots Of Numbers. Angela Brett
HIPPASUSHe Incensed Pythagoreans, Perhaps After Showing Unholy Sizes Angela Brett (Hippasus was expelled from the Pythagoreans, possibly because of disclosing the existence of incommensurable magnitudes)
HIPPOLYTAHighly Independent Person, Play's Outcome Leaves You Totally Amorous Tony McCoy O'Grady, referring to the character in Shakespeare's A Midsummer Night's Dream
IBRAHIMIraqi-Born Reasoner Analysed Hyperbolae, Integration & Motion. Angela Brett
MENAECHMUSMathematician Entered Near Alopeconnesus - Explained Cones Had Many Useful Sections. Angela Brett
NEWTON (2)Nice Equations - Worked Them Out Nimbly. Angela Brett
PLATOPerhaps Letters Are Totally Opinion Angela Brett, since the letters from which most of our knowledge of Plato come might not actually have been written by Plato, as is claimed.
PTOLEMYPostulated That Otherworlds Looped Earth & Moon Yearly. Angela Brett
PYTHAGORASPredict Your Triangle's Hypotenuse... Assuming Geometrically Orthogonal - Right-Angled - Sides. Angela Brett
PYTHAGORAS (3)Perhaps You Think He Achieved Greatness Of Reputation Alone... Sorry! Angela Brett, because much of the mathematics attributed to Pythagoras was actually by other members of the Pythagorean sect.
WOLFRAMWent Overboard Looking For Random Automata? Maybe. Angela Brett, referring to Stephen Wolfram and his huge tome 'A New Kind of Science' on cellular automata and similar constructs. I don't think there's really such a thing as going overboard investigating something in science... even if the hypothesis turns out to be completely wrong, somebody has to thoroughly investigate it so that we know it's wrong, and more than likely they'll discover something that is useful in the process. At the very least, absurdly wrong ideas make good material for (if only anyone had time to write for it.)