With rounding:
[tex]4[/tex] is less than [tex]5[/tex] so we round it down to whole number:
[tex]9.4\approx9[/tex]
[tex]6[/tex] is more than [tex]5[/tex] so we round it up to whole number:
[tex]62.6\approx63[/tex]
Now we have to add rounded numbers
[tex]63+9=72[/tex]
Without rounding:
[tex]62.6+9.4[/tex] to make it more visible I will write it differently:
[tex]62+9+0.6+0.4[/tex] is equal to [tex]62.6+9.4[/tex]
we can see that [tex]0.6+0.4[/tex] is equal to [tex]1[/tex]
so:
[tex]62+9+1=72[/tex]
As you see in this example those equations are equal so it doesn't matter if you take rounded numbers or not, it may be different in case like [tex]62.4+9.4[/tex] ( [tex]0.4[/tex] is just an example it could be any other number between [tex]0-4[/tex] ) because in this case it will be equal [tex]71[/tex] and another example [tex]62.5+9.5[/tex] (in this case [tex]0.5[/tex] is just an example, it can be any other number between [tex]5-9[/tex] :) ) and here, answer for this equation is [tex]73[/tex].
