# How To Use Expression Helper in MTools

MTools uses the mXparser library, so it can fully calculate with all the algorithms provided by mXparser.

mXparser Website: http://mathparser.org/mxparser-math-collection

In most cases, the calculation method used by Mifare Classic cards is XOR, sum, negation, CRC, etc. in logical operations.

When summing consecutive bytes, you need to repeat the input. In order to save time and memory, I have added an expression helper to MTools.

Original Expression: b15 = b1+b2+b3+b4+···+b13+b14

Expression Helper: b15 = sum(1:14)

The bytes must be consecutive, and the first and last parameters must be connected with a colon.

## Supported Algorithms

1.
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