Data Rates Calculation Question

[darkchild]

My A+ certification study guide says:

"PCI expansion buses operate at 33 or 66MHz over a 32-bit (4 byte) channel, resulting in data rates of 133 and 266MBps, respectively..."

How did they get 133 and 266MBps? I multiplied 4 bytes by 33 and 66 MHz and the products were 132MBps and 264MBps, respectively.

 

[hamster143]

The frequency is really 33.33 or 66.66 MHz. For some reason, these numbers were usually rounded down.