[haubey]

I think these people mean "I can't do arithmetic" which is much more acceptable, in my opinion. If you asked me to find a derivative, I could probably do it faster than I could find 123*26. It's not because the multiplication is harder, but because I don't have to do it in my head that often anymore. I have a calculator, and I use it. However, I have to do derivatives in math class everyday and at this point I'm probably faster at it. Not being able to do arithmetic is fine by me, I can't do it.

[learc83]

That's just because there are fewer steps for finding a simple derivative.

If you evaluate 12326 in your head, most people probably end up thinking through something like this

    123 * 20 + 123 * 6

    123 * 20 
    123 * 10 * 2
    1230 * 2
    2460 Now remember this part

    123 * 6

    100*6 + 20*6 + 3*6
    100*6 = 600
    20*6 = 120
    3*6 = 18
    600+120+18
    738

    2460 + 738 = 3198

Now compare that to taking a simple derivative.

Although I could ask you to take the derivative of 123x^26.