Maths problem (probably a mistake in the book)

[Arkadia]

I am thinking of a number. My number is the first multiple of both 5 and 100. What is my number?

@Arkadia

what does the book say?

Badly worded problem. As it stands 0, 100 and even -100 are all credible answers depending on the interpretation of “first. If rather than “number” it said “positive integer” or “positive whole number” it is more clearly 100.