BrainBashers - Medium Puzzles

Puzzle 317

Can you find three consecutive prime numbers …

… that equal 409,457 when multiplied together?

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Puzzle 318

What number comes next in this sequence:

7 8 5 5 3 4 4 ?

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Puzzle 319

A Proof That 2 = 1. Let A = B:

           A = B

multiply by A on both sides:

         A x A = A x B

subtract B x B from both sides:

   A x A – B x B = A x B – B x B

factorise:

  (A + B)(A – B) = B(A – B)

divide by (A – B) on both sides:

       (A + B) = B

replace A with B:

         B + B = B

factorise:

          2B = B

divide by B on both sides:

           2 = 1

Where lies the flaw in the logic?

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Puzzle 320

What is it that goes up and goes down …

… but does not move?

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