Hi Mitch, I dont quite understand the first step: (9999.9999)/10001 - (9999.9991)/10003 ≈ (10^4)/10001 - (10^4)/10003 Since you can round up 9999.9999 to 10^4, why couldn't 10001 and 10003 both become 10^4. I was a bit confuse because in the final step, you round both 10001 and 10003 to 10^4 as sh...