Question

round off the value 2.845 to three significant figures

Answer 1

here we have to drop 5 so that the given number will have 3 significant digits

so.. as the preceeding number... i.e. number just before 5 is even number..... so it will not be changed....
so the answer is 2.84
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if the preceeding number was an odd number... then it would have been increased by 1 ... (only in case when the number to be dropped is 5)
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hope it helps you...
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Answer 2

2.84
hope it helps you......