Numerical question units and intervals

This is my proposal for how the numerical question function and interface should be improved.

[_]Allow evaluation of expressions

 Checking this would accept  5/2   0.5*5  5^2/2   5^(5-3)/2  25*10^-1  sqrt(25)/2

[_]Allow fraction type 2 1/2 as 2.5

[_] Translate "½" as "+.5" but give warning "Avoid ½ character in numerical expressions!"

Answer 1:[ 2.5 ] Accepted error ± [0.5] Grade: [100%] Feedback:

Answer 2: [ 100.4..100.5) ] Accepted error ± Grade:

 Which would be interpreted  110.4 <= right < 100.5
 or that one could enter evaluation strings like
 110.4<=ans<100.5||100.5<ans<=100.6
 (I know that this particular thing can be addressed by having
 100.5 +/-0  first than 100.5 +/-0.1)

Feedback:

.... Answer 10: Accepted error ± Grade: Feedback:

[_] differentiated unit feedback, which is all of:

All of:  [_] feedback for lacking unit [_]Feedback for accepted UNIT but wrong number 
         [_] feedback for "possibly right number" if unit is adjusted
         [_] feedback for "Unit not recognized, either misspelled, wrong type, or just not expected"   

Unit: [ ] (optional)

 Should accept arrays like kg, kilogram, kilograms , kilogramme, "kilo gram" 

Alternative Units: Multiplier:[ ] Unit: [

Should possibly give feedback for misspelling including case errors  m milli  M Mega 

Multiplier: Unit: