It really is interesting how often a student believe there is something horribly wrong, but no hint is given why the student feels this way. Please provide sufficient information for the discussion.
In this case, if you have done anything "wrong", it would be failing to notice that you consistently rounded down.
... and you used 1.73, having lopped off 0.002051
... and you used 2.82, having lopped off 0.008427
The other values are exact.
In any case, you have grossly underestimated.
Also, why did you multiply by 10? Each unit represents 10. Don't multiply by it again.
3*(128/15) = 25.6 -- The exact value.
3*(8.19502) = 24.585 -- Your value, but with more decimal places
Isn't that interesting that we crossed 25, depending on how it is done? A very dangerous place to be.