First, you should chomp $ask:

chomp $ask;
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Next, you need to type in the word Add when prompted:

Type in a number: 2
Type in another number: 3
What would you like done?

Your choice is:
1) Add
2) Subtract
3) Multiply
4) Divide
Add
2 + 3 = 5
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Other advice:

• use strict and warnings
• Prefer chomp to chop
• Basic debugging checklist