\(a+b*10^6+c*10^{12}\) has three terms

a where 1<a<2
\(b*10^6\) where 1<b<2
\(c*10^{12}\) where 1<c<2

Now, compared to \(c*10^{12}\) a is negligible so we can ignore that.
Even \(b*10^6\) is small as compared to \(c*10^{12}\), but let's keep it for now and let's look at the answer choices

A. \(b*10^9\) this will be way less than \(b*10^{12}\) so will be way less than too \(c*10^{12}\)
=> NOT the closes to \(a+b*10^6+c*10^{12}\)

B. \(c*10^{12}\)
Let's keep this as this is close to \(b*10^6+c*10^{12}\)

C. \((a+b+c)*10^6\)
Now, even when we approximate a and b to be equal to c then the maximum value of this can still be
3c*10^6 which is way less than \(b*10^6+c*10^{12}\)

D. \( (b+c-a)*10^{18}\)
Now this gets multiplied with \(10^{18}\) which will become too big as compared to \(b*10^6+c*10^{12}\)

E. \((a+b)*10^{12}\)[/quote]
Now, lets assume a=1.1, b=1.2 and c=1.9
a+b = 2.3
=> \((a+b)*10^{12}\) = \(2.3*10^{12}\) will become too big as compared to \(1.1*10^6+1.9*10^{12}\)

So, answer will be B
Hope it helps!