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Comment by olog-hai | Hacker News Reader

"Divide the number 999,999,999,999,999,999,999,998,999,999,999,999,999,999,999,999 into 1"

Isn't this poor wording? The author is dividing 1 by the large number above, not the other way around.

"Divide b into a" means the same as "divide a by b".

Which I why I hate that wording, because that means "divide b into a" is equivalent to "divide a into b parts". And that's just confusing.

It feels to me as though far too much of any given field uses redundant (the same concept expressed lots of different ways) or misleading (something made to sound far more complicated than it actually is) terminology and causes unnecessary amounts of confusion among anyone trying to learn it.

But it loses its English meaning for a=1. Whereas, "divide ten into two" would make sense.

I'm with you on the wording. The word "into" is ambiguous on its own and even more ambiguous used with "divide." There's a discussion of that here: http://mathforum.org/library/drmath/view/52296.html

As an example, a person can easily read "divide 24 into 6" as "divide 24 into 6 [parts]," i.e. 24/x = 6, x = 4 — as opposed to 6/24 = x, x = 0.25. This use is especially reinforced by everyday experiences like dividing a cake into eight slices.

I've seen it both ways- "Divide four by two" is equivalent to "Divide two into four" in my experience.

Really? I've always read "divide by" and "divide into" as meaning the exact same thing:

"Divide four by two" = 4/2 = 2

"Divide two into four" = 2/4 = 1/2

Could this be a US/UK English difference?

It comes from "how many times does 2 go into 4", which is "4/2".

I think this phrasing is less confusing when it refers to labels rather than actual numerals. For instance 'divide the price into the exchange rate', which would mean the same as 'divide the exchange rate by the price'.

Why would you use this phrasing? I suppose it can flow more easily in some cases, for instance 'first work out X, then work out Y, then divide them both into Z and see which one is larger' is less of a mouthful than the alternative.

Perhaps it is some kind of regional difference. I've always lived on the US West Coast, and I've heard "divide four by two" expressed as "divide two into four" many times - and never the other way around.

I never use the "into" phrasing myself because it is confusing to me. But it does make some kind of sense if you think about it this way: "How many twos can you put into four?"

To me, "divide A into B" sounds like a some sort of anachronism that you might find in a 17th century one-room schoolhouse, while "divide B by A" sounds perfectly natural.

I went to school on the US East Coast, so you might be onto something here.

If you go to a pizza restaurant and ask them to "Divide two (large pizzas) into four (portions)" they would indeed give each person 1/2 pizza. So for colloquial use you are correct. Which makes the math definition confusing.

"Divide two into four" to me means that I am dividing two into four parts, which would equal one half.

"Divide the cake into two pieces" does not mean I'm giving you another cake.

x into y is y/x

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