The better you can “right-size” you instances, the more effective lower cost you can achieve.
To facilitate this, OCI is the first cloud provider where you can individually select the amount of CPU cores and separately select the amount of Memory for your instance. (Within some boundaries).

The pricing is modular:
Per OCPU you pay $0.025 per hour
Per GB of memory you pay $0.0015 per hour
If you are not familiar with the term OCPU, this is one CPU core that has hyperthreading turned on. So inside the OS you will see 2 CPUs (2 threads to the core). This is similar to what most cloud vendors call 2 vCPU.
So 1 OCPU = 2 vCPU 🙂
55.840 Different CPU and Memory Configurations!
So there is some boundaries to this flexible shape. For each OCPU you have minimum of 1 GB and can select up to 64GB of Memory. The max total size is 64 OCPUs and 1024 GB of RAM. According to my math this makes good for 57.856 different CPU/Memory combinations!!!
You can find pricing information here:
https://www.oracle.com/cloud/price-list.html#compute-vm