if n is a positive odd integer, then show that n²-1 is divisible by 5​

1 thought on “if n is a positive odd integer, then show that n²-1 is divisible by 5​”

1. Answer:

   if it’s an odd number we get n²- 1 even

   so for those numbers ending with 9 as last digit

   are divisible by 5

   while others are not divisible.

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