NCERT Example - Same parity - Number Play

Question: Why do all expressions a +/- b +/- c +/- d have the same parity? What happens when a, b, c, d are four consecutive integers?

Answer: All signed sums share one parity (even change under sign flip). For four consecutive integers that parity is even.

Full step-by-step NCERT solution with diagrams on Something by Zero.

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