Interesting Mathematical Fallacies
136132
Best Fake Proofs? (A M.SE April Fools Day collection)
112491
Finding counterexamples for infinite series.
83778
An incorrect proof by exhaustion
75600
Is Gödel's modified liar an illogical statement?
113344
How do we prove that something is unprovable?
123539
Numerical phenomenon. Who can explain?
102207
Gambler's fallacy and the Law of large numbers
76347
Shorter proof for some equvalences
29629
Distinguishing between valid and fallacious arguments (propositional calculus)
44399
Arithmetic and geometric sequences: where does their name come from?
55268
Differentiable and Continuous functions on [0,1] with 'weird' conditions.
109325
Euclid Lemma proof reasoning
39382
Examples of the Pigeonhole Principle
122226
Incorrect logic in popular proof of the irrationality of $\sqrt2$?
85540
Prove or Disprove the Existence of Solutions...
148239
natural deduction proof with De Morgan's laws
88188
Explain proof by contradiction.