Yes you can. You can use any combination of DDR2 memory (533, 667, 800 MHz) mixed, BUT total memory will run on the frequency of the slowest of the bunch. So, if you have 512MB@533MHz and you want to add 2GB@800MHz, you'll end up with 2,5GB@533MHz.
If by "type" you mean two different formats, like DDR and DDR2, then no. The memory controller cannot address both types at the same time, especially since they run at different speeds. The motherboard will default to the DDR2 RAM if both are installed.However, you can use different speeds of the same format, such as 667 MHz and 800 MHz. All modules will default to the lower speed.
667 = 667/1 in fraction
Yes but it will run at the lower speed.
91% of 667 is 606.97 .91 x 667
667 is composite. Its factors are 1, 23, 29, and 667.
1 x 667, 23 x 29, 29 x 23, 667 x 1 = 667
The prime factors of 667 are 29 and 23. 29*23=667.
667 is an integer, not a fraction. However, if you must express it as a fraction, it is 667/1.
1, 23, 29, 667
667 + 23 = 690
1 x 667
1, 23, 29, 667