Numbers/Letters converted to a number

[ROTHERS]

I have a drop down box, with 3 options, 3 years, 5 years or 7 years.
I want to use the 3, 5, 7 value elsewhere, so how do i convert the drop down cell to a number ?

[Andy Pope]

Depending on your dropdown

Data validation in cell A1

=CHOOSE(MATCH(A1,{"3 years";"5 years";"7 years"},0),3,5,7)

Form control, linked to cell A2
=CHOOSE(A2,3,5,7)

ActiveX control linked to A3
=CHOOSE(MATCH(A3,{"3 years";"5 years";"7 years"},0),3,5,7)

Validation