I sort of did for a lark a few years ago, then promptly forgot how to since I could do reasonable math approximations in my head. But my father used his pretty effectively.
Ask HN: Is there anyone here who still uses slide rules?
101–110 of 131 posts
Re: Ask HN: Is there anyone here who still uses slide rules?
#102I designed and 3D-printed my own slide rule to help me play Balatro! Balatro is a roguelike survival game where you need to multiply "chips" and "mult" together to meet a requirement each round. You get three chances to draft enough resources to survive. I designed my own slide rule to help with the mental multiplication - most of the fun of the game comes from the mechanics being slightly obscured from the player. S…
Wow, this is incredible.
Re: Ask HN: Is there anyone here who still uses slide rules?
#103I was issued one at King's Point Merchant Marine Academy in 1957 and used it constantly. A side benefit was the learned ability to estimate an answer and decimal point a skill which I still use. As I recall I mostly used multiplication, division, logs, and trig. I think I quit using it when I purchased a HP scientific calculator years later.
Re: your username
My mom found my shellback card among some stuff in her basement and asked if I’d like her to send it to me. Yes, please! Darned if I want to earn a replacement card.
Re: Ask HN: Is there anyone here who still uses slide rules?
#104Earlier quoted context omitted.
A key idea is that addition for logs is equivalent to multiplication. To multiply two numbers you line them up on a log scale and then read out the sum, which is equivalent to the product. There is much more they can do but that was one aha moment when my dad showed me his.
I've never used a slide rule but recently developed an interest in them (and also in nomograms [1]) My fascination stems from a belief: that slide rule usage helps users develop a certain intuition for numbers whereas the calculator doesn't. To illustrate, suppose someone tries to multiply 123 and 987 with a calculator but incorrectly punches in 123 and 187. My hypothesis is they'll look at the result but won't suspe…
With a slide rule you always have to estimate the expected answer in your head before you begin any calculation. So you develop a feel for how quantities scale with multiplication.
With a slide rule you can only multiply the significant digits, not the magnitudes -- which you have to do in your head. So you do exactly the same thing with the slide rule to multiply 123 and 987, 1.23 and 9.87, and 1,230 and 9,870. In all three cases, you get exactly the same answer: 121 or maybe just 120 (you only get 3 digits of precision at best). You still have to multiply the powers of ten in your head, to get the answers 121,000, 12.1, and 12,100,000.
I am just old enough to belong to the last generation of slide rule users. I used them in high school and college, then scientific calculators came along.
Re: Ask HN: Is there anyone here who still uses slide rules?
#105I designed and 3D-printed my own slide rule to help me play Balatro! Balatro is a roguelike survival game where you need to multiply "chips" and "mult" together to meet a requirement each round. You get three chances to draft enough resources to survive. I designed my own slide rule to help with the mental multiplication - most of the fun of the game comes from the mechanics being slightly obscured from the player. S…
Its really cool, appreciate the typeface choice.
Re: Ask HN: Is there anyone here who still uses slide rules?
#106I was issued one at King's Point Merchant Marine Academy in 1957 and used it constantly. A side benefit was the learned ability to estimate an answer and decimal point a skill which I still use. As I recall I mostly used multiplication, division, logs, and trig. I think I quit using it when I purchased a HP scientific calculator years later.
Re: your username My mom found my shellback card among some stuff in her basement and asked if I’d like her to send it to me. Yes, please! Darned if I want to earn a replacement card.
Shwllback3 was my radio callsign in Vietnam in '67 & '68.
Re: Ask HN: Is there anyone here who still uses slide rules?
#107Funny you ask ... I lieterally just now pulled out one of my slide rules to keep track of the required run rate for a cricket T20 game. Fastest and best feedback for whether the batting team is ahead of the rate.
Does it implement Duckworth-Lewis-Stern ;)
No, but a friend of mine made a nomogram to do that.
Re: Ask HN: Is there anyone here who still uses slide rules?
#108Earlier quoted context omitted.
Re: your username My mom found my shellback card among some stuff in her basement and asked if I’d like her to send it to me. Yes, please! Darned if I want to earn a replacement card.
Shwllback3 was my radio callsign in Vietnam in '67 & '68.
Nice. I got mine 4 miles off the coast of Mogadishu in '94.
Re: Ask HN: Is there anyone here who still uses slide rules?
#109Earlier quoted context omitted.
There is also the Vernier scale on certain styles of mechanical calipers.
I love the Vernier scales! But I honestly hadn't known about the sense in which slide rules have a Venier scale until your comment, which led me to [1]. In another class on laser-cutting I had students make a kerf-meter, which became more accurate with a Vernier scale. [1] https://dram.page/p/slide-rule-vernier/
Oh my God that is so clever. Thanks for sharing!
Re: Ask HN: Is there anyone here who still uses slide rules?
#110Yes, but only as a fun retro thing. Not for most calculations, although I have to say for back of the napkin, almost all in your head style things, they can be handy.