Explain how you would estimate to subtract 189 from 643

Well I would subtract first then estimate but you can't do then you estimate the biggest number so that would me 643 I would think that you where estimating to the nearest hundredth so your estimation would be 600 because you under lone the 4 and then this is a saying if it over five go up high if it's under 5 go down low and that is how I estmated now subtract

I would round it to the nearest hundreds