well yes you can so you round to 158 to 160 and divid 41to40and divid but now you know how to do the actual division so do you see how close the estimate it is .
If I assume that you're talking about 158 / 41 then my quick answer is yes, it is a good estimate. 4 times 41 is 164 which is closer to 158 than 3 times 41 (123) and 5 times 41 (205). Final summary: 4 is a good estimate for 158 / 41 because it is the closest whole number to the real answer.
Yes, you round 158 to 160, and 41 to 40, and divide. Now, do the actual division (perhaps with a calculator), to see how close the estimate is. Practice with several similar divisions, to get a "feel" of how much rounding will result in how much of an error.