Originally Posted by Val
I will modify my original idea based on comments thus far: let the kids add the zeros as subscripts, but then tell them to round to the place value of the digit where there is a value in each number being added. So you would get

  3.14160  
+2.71828
  5.85988

The answer would then be rounded to 5.8599.

This method would mesh with scientific practice, and again, would create awareness of an idea that will come up in later math and science courses.

Better?

This is absolutely right, says DH scientist - astrophysicist extraordinaire. For scientific research anyway, you use the number with the lesser amount of sig figs and so either rounding it first, or rounding after (I'm pretty sure they will always end up the same so it shouldn't matter the order), will give you the correct answer.

Precision matters in math and science. My 2.0 cents wink

Last edited by Marnie; 12/16/13 08:34 PM.