If she looks good to you then u have to make an exception for her. Add her, open her, have a fun back in forth for a bit and then move to number

She doesnt know you and has many options since she is a cute girl so she is very unlikely to respond and text u if you just say the number thing right of the bat + she is likely also gonna find it weird like "why tf doesnt he just wanna text on ig like everyone else?!"

If you don't add her, chances are your DM will be lost in her message request. Drop your ego and just follow her.

"Hey, told me that I would enjoy going out on a date with you ;)"

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