Trick or treat?

以下是一个常常说冷笑话的朋友说的，
有点废，本来不想放上来的，但为了应景，here it is


Why does Mathematicians always confuse about Halloween and Christmas?

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Halloween--31 OCT
Christmas--25 DEC

31 OCT=25 DEC



okay, you get it, you get it
you don't get it, forget bout it