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Euler created [[Euler's formula]], a basis for complex analysis.  Euler also laid a foundation for what later became combinatorial topology.

Euler created [[Euler's formula]], a basis for complex analysis.  Euler also laid a foundation for what later became combinatorial topology.

Interestingly, Euler had extraordinary powers of concentration.  He could recite word-for-word the entire Aeneid word-for-word.  He could work amid noise and distractions.  He could do phenomenal calculations in his head, which became very useful after he went blind.

Interestingly, Euler had extraordinary powers of concentration.  He could recite the entire Aeneid word-for-word.  He could work amid noise and distractions.  He could do phenomenal calculations in his head, which became very useful after he went blind.