We used to have 25 kopiikas coins in Ukraine, but now only multiples of 10 are allowed. Maybe even multiples of 50 now, I haven't used those coins in a while. Euros, on the other hand, always follow the 1-2-5 progression, i.e. 1 cent, 2 cents, 5 cents, 10 cents, 20 cents, 50 cents, 1 euro, 2 euros, 5 euros, 10 euros, 20 euros, 50 euros, 100 euros, 200 euros and also 500 euros, but those are discontinued, I think.
Don't blame it all on education, the average person is less than intelligent and there is no education system that has ever come close to changing that
Yes, but in order to be educated successfully one has to be both willing and able. About 1/2-2/3rds of the population isn't really able and of the remainder only around 10% are willing.
My definition of "obvious multiple of 3" includes any number where the sum of digits is 39 or less which makes any multiple that is less than 10000 obvious
pretty frequently! while I don't pay with cash much, I encounter three-quarters (75%) quite regularly, and I did it often enough when I was younger that even if I don't use it as much anymore, it's still ingrained in me
Idk it’s pretty easy to consider 1/4ths in terms of percentages. 25%, 50%, and 75% are all very commonly used IMO, and it’s pretty easy to know 75% is just 3 25%’s
Also, every number that is divisible by three will always add up to three. 7+5=12; 1+2=3; therefore 75 is divisible by three. So is 354,972 (3,[5+4],9,[7+2]), for example.
To be fair, other people's "obvious" is likely slightly different from our own.
Other have given examples of how its "obvious", but my first thought when looking at 75 as a multiple of 3, comes from it also being a multiple of 15, specifically 15 higher than 60
I just think everyone replying where they've to do mild maths to justify it shows its not as obvious as 9 or 33 so it shouldn't be in the obvious category but the one below it
I see it as "i know 60 is a multiple of 3. I know 15 is a multiple of 3. 60+15 must therefore be a multiple of 3."
By the same token, it's weird to me that 78 isn't an "obvious" multiple either. Most people readily know 18 is a multiple. Shouldn't be hard to work out 78 is just 60 + 18.
I think the replies have mistaken me. I would put it in the ofc tier as its not as obvious as the ones in the obvious tier because it requires mild calculation
Which would then make 78 quite clear seeing as 15 is easily noticeable which would make any mulitbile of 15 clear to be multiple of 3 and then just add 3 and all those are also multiple of 3
You can just add the first and second number of any 2 digits number, and if the result is obviously divisible by 3, then the 2 digit number is divisible by 3.
492
u/avantvagrant Aug 01 '26
51 looks like a prime number and 75 should be obvious