Context-Free Grammars(Clarification on answer)

Question

I'm trying to make sure if i did a) correct. I believe it makes sense, just trying to see if anyone has any suggestions.

The grammar

     G=<V,T,P,calculation>

for the calculator language is defined by:

V={calculation, expression, value, number, unsigned, digit, sign, operator} T={0,1,2,3,4,5,6,7,8,9,+,-,*,/,=,.}

P consists of the following productions (rules):

1. calculation -> expression =
2. expression -> value | value operator expression
3. value -> number | sign number
4. number -> unsigned | unsigned . unsigned
5. unsigned -> digit | digit unsigned
6. digit -> 0| 1| 2| 3| 4| 5| 6| 7| 8| 9
7. sign -> + | -
8. operator -> +| -| *| /

Show:

(a) 100/2.5= is in the calculator language;

My answer:

a.

<calculation>

  => <expression> =
  => <value> <operator> <expression>  
  => <value> / <expression>
  => <number> / <expression>
  => <number> / <value>
  => <number> / <number>
  => <unsigned> / <unsigned . unsigned>
  => <digit><unsigned> / <digit . digit>
  => 1<digit><unsigned> / 2.5
  => 10<digit> / 2.5
  => 100 / 2.5