Mental Math Basics, what is your most useful tip?

[amascuba]

We have all lived the story at least once or twice (or 3 or 4....) times

Unfortunately for Jeff, he doesn't utilize the standard drink mixes and experiences that scenario every time he dines out.

 

[Doc Intrepid]

I've just got about 4 or 5 schedules written in my wetnotes. Do this stuff often enough on standard gasses and you start to realize its mostly all the same schedule/curve.

Fortunately, I figured this out just about the time that I began experiencing "senior moments" with great frequency. Wetnotes tend to be more reliable for me than either mental tricks or computers...

But whatever you use, make sure you can use it when you find yourself highly concerned regarding imminent death. Emergencies have this annoying habit of not occurring the way you'd envisioned they would (and practiced in advance for).

 

[JessH]

That has got to be the most convulted table I've seen in awhile. Of course I don't understand it and can't think in metric for diving worth a damn either.

Don't think I'll use it to 50m anytime soon.

I just saw that it was in metric and immediatly gave up I can do the conversion in my head, but using metric makes me feel really dirty.....

In TX the tax rate is 8.25% so I always just double the tax amount and pay a 16.5% tip. It's very easy to do on the fly!

I do the same with some rounding up if the service was good. You just have to remember when you leave the state that the tax rate may be less or more depending on where you are. Because of this I have recently started to do the shifting the decimal place and multiplying by 2 so that I won't be caught doing the wrong thing while narced and in a foreign land (such as Nebraska).

~Jess

 

[neil]

...........46?

 

[Rick Murchison]

I've just got about 4 or 5 schedules written in my wetnotes. Do this stuff often enough on standard gasses and you start to realize its mostly all the same schedule/curve.

Fortunately, I figured this out just about the time that I began experiencing "senior moments" with great frequency. Wetnotes tend to be more reliable for me than either mental tricks or computers...

But whatever you use, make sure you can use it when you find yourself highly concerned regarding imminent death. Emergencies have this annoying habit of not occurring the way you'd envisioned they would (and practiced in advance for).

Math shortcuts and mental conversions & math are sort of a hobby of mine; the TLAR (That Looks About Right) principle serves me well, especially when looking at a computer and deciding whether to believe it or not.
... but ...
I'm with Doc completely here. I use my written schedules (including gas consumption checkpoints) on the simplest deco dives. All that "battleground calculation" and "mental math" and stuff just makes it where what I see on the written tables is just what I expect to see.
In an emerging emergency, I use a process called "planned perceptual narrowing" - another subject for another thread.
Rick

 

[Cacia]

oh, well-- sounds good, can't wait.

 

[ArcticDiver]

Math shortcuts and mental conversions & math are sort of a hobby of mine; the TLAR (That Looks About Right) principle serves me well, especially when looking at a computer and deciding whether to believe it or not.
... but ...
I'm with Doc completely here. I use my written schedules (including gas consumption checkpoints) on the simplest deco dives. All that "battleground calculation" and "mental math" and stuff just makes it where what I see on the written tables is just what I expect to see.
In an emerging emergency, I use a process called "planned perceptual narrowing" - another subject for another thread.
Rick

TLAR=SWAG?

 

[JessH]

TLAR often works well with methods designed to KISS

 

[Rick Murchison]

TLAR=SWAG?

TLAR is more accurate than a SWAG. It is borrowed from attack aviation for the "sight picture" that'll get the bombs on target. TLAR is that experience generated tweak on the available data that yields dependable results, where a SWAG is much more hit-or-miss
Rick

 

[ArcticDiver]

TLAR is more accurate than a SWAG. It is borrowed from attack aviation for the "sight picture" that'll get the bombs on target. TLAR is that experience generated tweak on the available data that yields dependable results, where a SWAG is much more hit-or-miss
Rick

LOL

I always thought the experience came in on deciding where to stick the gum on the windscreen, hence the "S"