sir i am unable to understand one question

sir ye rule division or multiplication mai hi apply hoga ya phir addition multiplication division and subtraction sab mai ..???

sir multiplication vale part mai A ki value 278.46 and delta A ki value 0.03 aa rhi hai toh sir ise rounding off kr ke likhenge ya phir as it is likh denge ..?

sir true value 2.06 aa rh hai

How to experimentally take out the value of constant .