100:1000

It seems like you may be referring to a ratio or a proportion (100:1000). This can be simplified.

100:1000 can be simplified by dividing both sides by 100:

100 ÷ 100 : 1000 ÷ 100 = 1:10

Thus, the simplified ratio is 1:10. If you were looking for something different or have a specific context in mind, please provide more details!