On the Subject of Grimm

The grimm reaper of math or something like that.

• Take the three digits to the left, right, and above the grimm symbol, and add, subtract, multiply, and divide the digit inside it to obtain 12 separate values (the digit inside should be the second argument of any operation). These values can be negative or fractional.
• Arrange these values from greatest to least.
• Take the highest value and subtract the second highest value from it. Keep subtracting the next highest from the previous result until you run out of values.
• If when subtracting a value, the result is negative, add that value instead.
• After the last subtraction round the number down and take it modulo 10. Call this the grimm.
• If the digit on the bottom of the module matches this grimm, press the yes button. If it is not, press the no button.
• Incorrect presses will result in a new combination being generated.