Hi Daniel Zurdo
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When you create a new reservation in Azure, the "recommended quantity" takes into account any existing reservations you’ve made. Once you commit to a new reservation, the recommended amount is reduced because the reserved resources are no longer available for new reservations.
Azure calculates the best reservation recommendation by looking at your usage over the past 7, 30, and 60 days. It compares what your costs would have been with a reservation versus your actual pay-as-you-go costs, and then recommends the quantity that gives you the most savings.
https://www.anodot.com/blog/azure-reserved-instances/
https://learn.microsoft.com/en-us/azure/cost-management-billing/reservations/determine-reservation-purchase
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