BitAnd
  

The bitwise "and" operator compares each bit of the first number to the corresponding bit of the second number. If both bits are 1, the corresponding result bit is set to 1. Otherwise, the corresponding result bit is set to 0.

syntax
BitAnd(number1;number2)

example
BitAnd(21;13) = 5
explanation:
21 = bin 10101
13 = bin 01101
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5  = bin 00101