Volume 49
, Issue 1


The Australian Academy of Science and The Australian Mathematical Sciences Institute are currently preparing a Decadal Plan for the Mathematical Sciences in Australia.
The earth, as we all know, rotates about its axis once every twenty-fourĀ hours, giving us the cyclic alternation of night and day.
This method generalizes the disk method of integration to find the volume of a rotated function by utilizing a differential dependent on both the axis of rotation and the rotated function.

Q1411 How many three-digit numbers are there which do not contain any digit more than once?  What do you get if you add them all up?

Q1400  Using the method of previous problems (for example, problem 1393), we rewrite the recurrence as
\[ a(n)-ra(n-1)=s[a(n-1)-ra(n-2)] \]
with \( r=s=3 \).