Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have been looking at Lancelot Hogben's Mathematics for the Million (first published in 1936).

In the chapter on calculus he says that the second derivative $\displaystyle \frac{d^2y}{dx^2}$ is

pronounced dee-two-wy-by-dee-eks-two.

The final "two" surprised me as I was taught to say "squared" and I have never heard it pronounced differently.

Assuming that it's not a typo and that Prof Hogben wasn't mistaken, did people really say "two" in those days and does anyone say "two" these days?

I suppose that for higher derivatives just saying the number rather than the power it represents may be easier.

share|cite|improve this question
Well, maybe he meant that $\dfrac{d^2y}{dx^2}$ is $\dfrac{d^2y}{dx}$ too. ;-) – Asaf Karagila Jul 18 '13 at 10:27
i've heard a lot of people saying it this way – Aang Jul 18 '13 at 10:31
I usually say "the second derivative of $y$ with respect to $x$" ... – Neal Jul 18 '13 at 11:03
I say "squared" in the place of the first "two" too: "dee-squared-wy-by-dee-eks-squared". If we can find someone who says "dee-squared-wy-by-dee-eks-two", all $2^2$ possibilities will have been covered. – ShreevatsaR Jul 18 '13 at 11:53

According to this post there are several ways to pronounce $\frac {d^2y}{dx^2}$, including:

1.) "dee squared wai over dee eks squared"

2.) "the second derivative of y with respect to x"

3.) "dee two wy by dee eks two"

share|cite|improve this answer
I did see that post, but I can't see "dee two wy by dee eks two" on there. – Peter Phipps Jul 18 '13 at 14:05

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.