How to apply discount based on purchased quantities?

I have a product discounted lines included in the drop-down that are listed:

1. Buy 1 Get 1 half off

2. Buy 6 take 30% off order

3. Buy 12 items take 50% off order

How to calculate this under calculations value?

Thank you,

Ja'Von

I have been checking your forms and did not find one with the options you mentioned, I only found this form with a payment integration on it: https://www.jotform.us/form/92787387416170 

If you're using the product's option then you may enable the special pricing option based on quantity so you can apply the discount, here is a guide about it: https://www.jotform.com/help/265-What-is-Special-Pricing 

You may also share us the form you're working on so we can check and provide different steps depending on the payment type used in case the special pricing does not work.