How to round "correctly" (to certain level of accuracy)

Question

Say I have the number 0.73992 and I'm rounding to 3 decimal places. My instinct would be to write 0.740 (3dp). But surely that implies that it is exactly 0.740. The only other alternatives are to write 0.7399 (4dp) or 0.74, neither of which are to the requested accuracy.

I'm sure there's a nice definitive answer out there, I just can't seem to find it :/

Answer 1

If it was 0.11488 you would round to 0.115, and it does not implies that it is exactly 0.115. I think you just confused because the rounded number ended on 0. So, in your example, you should write 0.740.

Answer 2

.0740 would be the answer. Since you're adding the 0 at the end it implies that you have an accuracy to the third decimal place.