Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Designation | Bus width (bits) | Channels | Clock rate (MHz) | Bandwidth (MB/s) |
| --- | --- | --- | --- | --- |
| PC600 | 16.0 | Single | 266.0 | 1066.0 |
| PC700 | 16.0 | Single | 355.0 | 1420.0 |
| PC800 | 16.0 | Single | 400.0 | 1600.0 |
| PC1066 (RIMM 2100) | 16.0 | Single | 533.0 | 2133.0 |
| PC1200 (RIMM 2400) | 16.0 | Single | 600.0 | 2400.0 |
| RIMM 3200 | 32.0 | Dual | 400.0 | 3200.0 |
| RIMM 4200 | 32.0 | Dual | 533.0 | 4200.0 |
| RIMM 4800 | 32.0 | Dual | 600.0 | 4800.0 |
Question:
Name the least clock rate mhz when designation is rimm 4200
Answer:
533.0