Your calculations contain some inaccuracies, so let's break it down with the correct conversions.

1. **Memory Size Conversions:**
- 1 MB (megabyte) = 1024 KB (kilobytes)
- 1 KB (kilobyte) = 1024 B (bytes)

2. **Conversions detailed**:
- **4 MB**:
- 4 MB = 4 × 1024 KB = **4096 KB**
- **2 MB**:
- 2 MB = 2 × 1024 KB = **2048 KB**
- **3 MB (you mentioned 3 KB)**:
- 3 MB = 3 × 1024 KB = **3072 KB**
- **2048 MB**:
- 2048 MB = 2048 / 1024 GB = **2 GB**

3. **Correction of your original statements**:
- Your mention of "3 KB = 3072 B" is incorrect; instead:
- 3 KB = 3 × 1024 B = **3072 B**

To summarize:
- 4 MB = 4096 KB
- 2 MB = 2048 KB
- 3 MB = 3072 KB
- 2048 MB = 2 GB

If you have further questions or need additional calculations, feel free to ask!