See also the Dr. Math FAQ: 3D and higher Browse Middle School
Number Sense/About Numbers Stars indicate particularly
interesting answers or good places to begin browsing. Selected
answers to common questions: Multiplying by zero. Casting out
nines. Number facts from the Web. - 0.9999... equal to 1?
[6/28/1996] One of my teachers insists that the value of
0.9999999999... is one. The other insists that anyone who thinks
that 0.9999999... is one is an - 1 and 0: Prime or Composite?
[10/06/1997] Is the number one a prime or a composite number?
Why? What about zero? - About Rational Numbers [3/20/1996] Can
you explain "rational numbers" to me? How do you express them?
What kind of operations can you perform on them? - Adding and
Subtracting Roman Numerals [10/07/1997] Do you have any
suggestions for how to teach adding and subtracting of - Adding
Arithmetic Sequences [07/10/1998] How do you add the numbers
from 1 to 5000 without actually doing it or using a calculator?
What if you were adding just the odd numbers?