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Here's how I calculate 15% tips in my head. After getting used to this approach, I could consistently beat friends who were fumbling with their smartphones.

BTW, math majors have a reputation for NOT being able to do mental arithmetic, so being a math major who could do this was a fun and ironic way to defy stereotypes.

Preparation. Memorize the product of each digit with 1.5

1 x 1.5 = 1.5
2 x 1.5 = 3.0
3 x 1.5 = 4.5
4 x 1.5 = 6.0
5 x 1.5 = 7.5
6 x 1.5 = 9.0
7 x 1.5 = 10.5
8 x 1.5 = 12.0
9 x 1.5 = 13.5

Step 1. Round your bill to two significant digits (35.76 -> 36)

Step 2. Recall the product of the first digit with 1.5 (3 x 1.5 = 4.5). The tip is going to be pretty close to the product you recalled (4.50)--you just need to adjust it upwards a bit using the second digit.

Step 3. Recall the product of the second digit with 1.5 (6 x 1.5 = 9), divide the product you recalled by 10 (9 / 10 = 0.9), and add it to the result of Step 2 (4.50 + 0.90 = 5.40) to get your final result.

Congratulations! You've just calculated your 15% tip to within an accuracy of 10 cents. If you want more speed, you can round your bill to just the first significant digit and skip Step 3--this will give you a 15% tip to within an accuracy of 1 dollar. Alternatively, if you want to impress your friends with more accuracy, you can keep more significant digits around and continue adjusting.

gjm10y00

Is this really much easier than shifting the decimal place and then adding half the number? (Rounding at the start if you want, which you probably do.)

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8 Lifehack Ideas January 2015

by Gondolinian

1st Jan 2015

1 min read

8

Life hacking refers to any trick, shortcut, skill, or novelty method that increases productivity and efficiency, in all walks of life.

— Wikipedia

This thread is for posting any promising or interesting ideas for lifehacks you've come up with or heard of. If you've successfully implemented your idea, please share the results. You are also encouraged to post lifehack ideas you've tried out that have not been successful, and why you think they weren't. If you can, please give credit for ideas that you got from other people.

To any future posters of Lifehack Ideas threads, please remember to add the "lifehacks_thread" tag.

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[-]James_Miller10y150

Any shy nerds interested in leveling up their social skills should consider working as a volunteer petition signature gatherer. In the U.S. at least, to run for a political office you often need to get a huge number of people to sign a petition. If you are one of the people getting signatures you have to approach strangers, quickly pitch your candidate, and then ask for a signature. This is a great, socially acceptable way of overcoming shyness plus you can help out your political tribe. To do this, contact a local branch of the political party you most support and offer your services.

[-]pinyaka10y20

Have you done this? I would expect that this might work well if your political tribe is popular in your area, but you may be met with some hostility if not.

[-]James_Miller10y50

Yes, for myself when I ran (unsuccessfully) for the Massachusetts State Senate in 2004. My tribe was very unpopular, but the people who said no (and most did) didn't express any hostility.

[-]necspe10y00

For lack of a better word I worked as a dealer walking around crowded places where there's flow of people, finding new patients for my physician. It was difficult since people had to sign some papers and change their physician on the spot. I personally would never sign such thing on the street, but to my surprise cca 4 people per day or one in one hundred did. I met with some hostility, but after I got used to it it was a great experience and definitely worth it despite the low pay. My conversation skills have improved greatly.
Edit: It was a new physician with good reputation so far that I visit myself to this day. Half of the people who signed up just turned 18 and didn't have any physician and the rest just moved to the area. Also, if my writing is incoherent, it's possibly because English is not my first language.

[-]moridinamael10y120

I don't read books anymore, I use the built-in text-to-speech accessibility feature that all modern smartphones have and let my phone read the book to me at a speed close to my normal reading speed. You can of course do this while driving or doing other chores.

[-]pinyaka10y50

Did you have a period when you were starting where you couldn't follow what the TTS engine was saying? I've tried this a few times, but found the pacing and diction to be nearly intolerable.

[-]moridinamael10y100

Yes, that's common. Your brain adjust gradually and the upper limit of the TTS software is unfortunately lower than the upper limit of human comprehension, meaning, in other words, I wish the voice spoke faster even at the cost of sounding human. Since the voice is perfectly consistent, unlike real human voices, your auditory system eventually processes what it says perfectly.

[-]is4junk10y40

I watch nearly all youtube videos on 2x speed and sometimes wish it would go faster (all video services that don't have this are evil). If you are right about voice consistency allowing for going even faster that would be awesome. Will just need accurate voice->text to speed it up even more.

[-]Gondolinian10y10

I watch nearly all youtube videos on 2x speed

I was going to try this, but I can't figure out how. Do you need a YouTube account or some kind of browser plugin?

[-]is4junk10y10

Nothing is required that I know of. Here is a video. At the bottom right there is the settings icon - gear shaped. Speed is an option.

I have seen on a small minority of videos the option wasn't present in settings however researching on the title can sometimes get a link to a video that is.

[-]Gondolinian10y10

Weird, when I click on settings for that video, I only see options for Annotations, Subtitles/CC, and Quality. When I click on the Options link to the right of Subtitles/CC, I see all kinds of options for fonts and colors, but nothing for speed.

[-]is4junk10y10

I normally use chrome. But I did see the problem with IE. IE is using the default video player. You want to use the htlm5 player.

Go to this page and select the 'use html5' button and try again. https://www.youtube.com/html5

[-]Gondolinian10y00

It works now. Thanks!

[-]sumguysr10y00

On windows you might like to try Daum's Potplayer. It's extremely lightweight software with tons of handy features and will play both youtube videos and playlists and scale speed all the way to 12x.

I use it for most youtube videos just to decrease my firefox memory usage and improve its responsiveness.

[-]Risto_Saarelma10y90

Started unplugging my DSL modem for periods of offline work or reading e-books off an internet capable device when I don't want to be distracted by impulsive browsing. If stuff comes up that I want to look up, I write a line on a post-it note. Seems to be just the right level of annoyance to get up and plug the thing back in that I won't do it without thinking.

[-]Gunnar_Zarncke10y20

I used to block my favorite sites in /etc/hosts during periods of procrastination. Worked well enough and doesn't prevent necessary online work (VPN...).

[-]Alsadius10y00

I use StayFocusd(Chrome plugin) for similar purposes.

[-]iarwain110y00

I use Microsoft Family Safety (one of the parental controls that comes with Windows) to set up times when I can or can't use the computer / internet / specific sites. My wife has the password and enforces it. I've also used Internet Lock in the past for the same purpose.

[-]savedpass10y70

Ask yourself how much better or worse you are going to feel after completing a task you're procrastinating on. Write the answer down and put it to the test. After doing this several times I'm finding that I wrongly assume I'm going to feel worse after finishing the task, which makes me procrastinate.

[-]Calien10y30

This reminds me of a CBT technique for reducing anxiety: when you're worried about what will happen in some situation, make a prediction, and then test it.

[-]Gondolinian10y60

Three-minute TED talk about how to properly tie your shoes.

[-]polymathwannabe10y10

I only wear laceless shoes. It's a huge timesaver for me.

[-]FvEYfaEQSeeWcnZ10y40

Paruresis is a type of phobia in which the sufferer is unable to urinate in the (real or imaginary) presence of others, such as in a public restroom.

A proven method of physically treating paruresis is through breath holding. The paruretic person takes a deep breath in, exhales about three-quarters of it, and then holds their breath for a given length of time, usually 60 seconds or less, and in doing so, the internal sphincter muscle of the urethra relaxes enough so that the person can urinate freely. http://en.wikipedia.org/wiki/Paruresis#Treatment

[-]robot-dreams10y20

I wanted to stop using Facebook, so I deleted my account and then blocked the domain.

Now I don't have any friends anymore, and I have a lot of free time.

[-][anonymous]10y20

For those of you in the content creation/sharing business:

Using newsblur, I go through a ton of content every day. I'll click the "save button" if it's interesting, then tag it according to a standard categorization scheme.

Here's what happens via IFTTT and Zapier:

It get's added to my Buffer (bufferapp.com) to get scheduled on facebook, twitter, g+, and linkedin
It gets saved to my evernote, for later searching
It gets added to my contactually articles, so that I can share it with people in my network when it's time to ping them
Based on what category it's tagged with, it gets posted to the relevant subreddits
It get's added to a google spreadsheet for the category, for a later "best links of the month" post.

Really easy way to keep relevant social channels up to date without putting in a ton of extra work.

[-]is4junk10y20

For several years I had lower back pain reoccurring regularly - pulled muscle. I tried the standing desks and it helped but not that much. Then I heard it was due to weak core muscles. Once I started doing the exercises it helped quite a bit. I just did the ones where I was on my back and I did them in bed.

But once I stopped having back pain as often then I stopped doing the exercises. Mainly because the exercises are boring and easy to skip. For the last year I have had luck using the slendertone waist band. It seems to work. I play video games to take my mind off the 30 minutes of discomfort - plus it is positive reinforcement .

edit for clarity

[-]Antiochus10y00

I once had the same problem with a weak core. Fencing cured it for me within a few months, though for the first two months I ended the classes with pain in that area.

[-]IlyaShpitser10y30

Fencing is extremely bad for your knees :(. -- An ex-foilist.

[-]Antiochus10y00

I've heard that. I suppose it's for the best that I moved into a style less lunge-happy (German and Italian longsword.)

[-]robot-dreams10y10

I wanted to invest my money, but I didn't want to waste any effort thinking or worrying about it, so I made an account on Wealthfront, set up a monthly recurring transfer, and then put it out of my mind.

[-]FvEYfaEQSeeWcnZ10y10

Have no internet at home and no smartphone.

[-]robot-dreams10y00

For Linux users (or Mac OS X users that use the Terminal) who want to pick up a journaling habit:

I set up the following aliases to DRAMATICALLY reduce the "activation energy" for writing a journal entry:

alias jcd='cd <journal directory>'
alias today='jcd; vi `date +%Y-%m-%d`; cd -'
alias yesterday='jcd; vi `date -r \`expr \\\`date +%s\\\` - 86400\` +%Y-%m-%d`; cd -'

So if I want to write a journal entry, I just type 'today' and get started. Note that this also has the secondary benefit of keeping journal entries nicely organized by date.

BTW, I am no writer, but this technique has gotten me to write a decent amount over the years:

$ jcd; cat * | wc -w
    92804

[-]robot-dreams10y00

Here's how I calculate 15% tips in my head. After getting used to this approach, I could consistently beat friends who were fumbling with their smartphones.

BTW, math majors have a reputation for NOT being able to do mental arithmetic, so being a math major who could do this was a fun and ironic way to defy stereotypes.

Preparation. Memorize the product of each digit with 1.5

1 x 1.5 = 1.5
2 x 1.5 = 3.0
3 x 1.5 = 4.5
4 x 1.5 = 6.0
5 x 1.5 = 7.5
6 x 1.5 = 9.0
7 x 1.5 = 10.5
8 x 1.5 = 12.0
9 x 1.5 = 13.5

Step 1. Round your bill to two significant digits (35.76 -> 36)

[-]gjm10y00

Is this really much easier than shifting the decimal place and then adding half the number? (Rounding at the start if you want, which you probably do.)

[-]AmagicalFishy10y00

Haha, that's what I do.

If my cost is $14.32, I know $1.43 is 10%, and half of that is about $0.71, so the tip's $2.14 (though I tip 20%, which is even easier).

[-]gjm10y00

Right.

In the UK, we have a sales tax called VAT (for "value-added tax"). For a while its rate was 17.5%. The way you work that out is: shift the decimal point (10%), halve (5%), halve again (2.5%), and add up :-).

(Tips in the UK are usually about 10%, so that's a bit easier. And now our VAT rate is 20%.)

[-]Elo10y00

To expand on this method.

Take a number like 1230 10% of that number is 123.0 (found by shifting a decimal place) half of that is 61.5 add that to 123.0 =184.5 = 15%

[-]polymathwannabe10y-20

Proposal: give waiters humanly decent salaries so they don't need the tips in the first place.

[-]gjm10y00

I'm strongly in favour of this but there isn't much I can do to make it happen. I imagine robot-dreams is in the same boat.

[-][anonymous]10y00

Meta

[-][anonymous]10y30

Meta: Why is this a monthly thread? Seems like it might make more sense as a repository.

[-]Gondolinian10y00

What are the advantages of a repository format over a monthly thread format?

[-][anonymous]10y00

It's entirely searchable, you don't rehash previous discussion, and the upvotes act globally so the best lifehacks rise to the top.

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