can i convert the default value of dropdown field into integer value such as zero / 0 ?

can i convert the default value of dropdown field into integer value such as zero / 0 ?

//question:
I have this Script that I want to calculate:
  1. (IF(How_many_days_is_your_group_skiing  != "-Select-",How_many_days_is_your_group_skiing.toLong(),0) *
    (
    (IF(Kids_Skis_Age_12_and_under  != "-Select-",Kids_Skis_Age_12_and_under.toLong(),0)  *  23)  +  
    (IF(Adult_Skis  != "-Select-",Adult_Skis.toLong(),0)  *  30) +
    (IF(Performance_Skis  != "-Select-",Performance_Skis.toLong(),0)  *  41)  +  
    (IF(High_Performance_Skis  != "-Select-",High_Performance_Skis.toLong(),0)  *  50)  +  
    (IF(Kid_s_Snowboard_Age_12_and_under  != "-Select-",Kid_s_Snowboard_Age_12_and_under.toLong(),0)  *  23)  +  
    (IF(Adult_Snowboard  != "-Select-",Adult_Snowboard.toLong(),0)  *  30)  +  
    (IF(Helmets_10_per_Helmet_per_Day  != "-Select-",Helmets_10_per_Helmet_per_Day.toLong(),0)  *  10)
    )
    )









Why this not working on on success event but working on update in form element.

i want to converting default value of dropdown field "-Select- into zero/0 value so i can calculate the price.