Choosing resistors in series to make standard values
If you are making these combinations based only on the marked (nominal) value of the resistors then you may not going like the results.

For example, an 11.8k\$\Omega\$ resistor with a 1% tolerance can actually have a resistance that is +/- 118\$\Omega\$ different from the marked value. Adding a 100\$\Omega\$, 1% resistor in series will give you a nominal resistor of 11.9k\$\Omega\$ +/-119\$\Omega\$. So, the actual resistance value could be as low as 11.781k\$\Omega\$.

If you really need 11.900k\$\Omega\$ you will need to buy resistors with a much smaller tolerance or measure each one. Oh, and be sure to calculate the accuracy of your ohmmeter.