[OS X TeX] Ordering index entries

[John Thoo]

Hi, everyone.

I'm sorry to ask here, but my Web search was not fruitful.

I have the following index entries in my document:

  \index{Base (of a numeral)!base 4}
  \index{Base (of a numeral)!base 6}
  \index{Base (of a numeral)!base 10}
  \index{Base (of a numeral)!base 60}

but in the Index it appears as

  Base (of a numeral)
       base 10, 18
       base 4, 8
       base 6, 5
       base 60, 16, 18

I use  makeindex.  How can I get "base 10" to appear in between "base 6" and "base 60" so that it is listed "alphabetically"?

Thanks in advance.

---John.
(I receive the digest)