|1. If you are familiar with metric measurements, the memory scales for hard drive sizes and memory chips work the exact same way. |
The base measurement is Bytes. 1 KB=1000 Bytes. 1 MB=1000 KB or 1,000,000 Bytes. 1 GB=1000 MB or 1,000,000 KB or 1,000,000,000 Bytes. 1 TB=1000 GB or 1,000,000 MB or 1,000,000,000 KB or 1,000,000,000,000 Bytes.
Each unit always goes up by a measure of 1,000.
2. Why are you using a CD or DVD? A USB memory stick will hold WAY more and will read and write much faster than a CD or DVD ever will. Depending on the size, you might even be able to get them for about the same price (or cheaper) than a big stack of CDs/DVDs. There's also the option of an external hard drive - they're usually between $50-200 and you can get those in excess of 2 TB if you want. Those will hold thousands of pictures and beyond. In the past year a technology called Solid State Drives (or SSD) were invented which means the drives have literally no moving parts in them - they've been proven to crash less (which means they last longer) and have faster read and write speeds than previous external hard drives. The best part is they're about the same price as non-SSD drives were in their primes.