Round off the numbers to 1 significant digit and then estimate the value of the following expression without using a calculator. Show your work, writing your answer in scientific notation.
(287,900,001,000)*(168,000)=a*10^k
where a=___ and k=___
You round 287,900,001,000 to 300,000,000,000 which is 3×1011
You round 168,000 to 200,000 which is 2×105
So you have to multiply 3×1011 by 2×105
so you multiply the 3 by the 2 getting 6 and add the exponents of 10,
getting 11+5 or 16. So a = 6 and k = 16.
So you get 6×1016.
Edwin