Arithmetic

Can you calculate 123 x 24 without writing? I took 20 seconds.

What about 173 x 17? I took 45 seconds.

1234 x 23? I took over a minute.

I will get back to this post in 10 years and time myself again :-)

We are all very different. Some people will say: "off course, faster than you". Many people will say "you are crazy".