Time how long it takes you to get an answer to the following subtraction problem, in your head. No writing stuff down, or using a calculator.
427 - 316 =
Then, when you've done it, reply to this thread saying
(A) What number did you get as the answer?
(B) How long did it take you?
(C) How did you get it?
So, for example, you might reply:
(B) 10 seconds
(C) I counted onwards in 10s, then in 1s.
I'm adding a few bumps, to help you avoid seeing other people's answers before you have a go yourself.