Question 496961: What is a batty number? And what are four example's of batty numbers?
Answer by richard1234(7193)   (Show Source):
You can put this solution on YOUR website! Look it up on Google. The word "batty number" is either very rarely used or never used in mathematics.
Update: I looked it up; they are more often referred to as "vampire numbers." Not all the "numbers" are factors of the whole number, as you said (since 4 is not a factor of 1435), but rather, they satisfy this property:
1395 = 15*93
1435 = 35*41
2187 = 27*81
In each of these cases, the four-digit number is equal to the product of two two-digits numbers, such that the four digit number and the two-digit numbers use the same digits.
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