On mental arithmetic
25 03, 11
The culprit
I don’t understand how you can order wallpaper in a hardware store without knowing that ‘seven eights are fifty six’, or that 15% of 360 is about 60. It’s a tool you need to eyeball your calculations to see if they are in the right ballpark.
More directly related to work, we often want to translate the weight of a protein into the number of mol. We could say, OK, weight in grams divided by molecular weight, but isn’t it easier to build a little rule:
“If the molecular weight of a protein is X kDa, then X micrograms is a nanomol”
These are the quantities we deal in. So, I know that 20ug of darcin (M=18.9kDa) is a nmol.
I also know, by jumping one prefix, that 20ng of darcin is a pmol.
No exponents, just the prefixes. Simples
Rant off, I’m going to consume a mol of ethanol now.