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# Estimation

Being able to estimate can help you determine the likely range of the answer. Identify the most significant contribution, and fine tune the answer from there.

Multiplication/Division - Estimate the value of $$123456789 \times 54321$$.

A) $$2.2 \times 10^3$$
B) $$5.4 \times 10 ^ 4$$
C) $$1.2 \times 10 ^{11}$$
D) $$7 \times 10^{12}$$
E) $$6 \times 10^{14}$$

Solution: A good way to deal with this is to convert into scientific notation. We estimate the value as $$1.2 \times 10^8 \times 5.4 \times 10^4 \approx 6 \times 10^{12}$$. Hence, from the given options, the best answer is D.

Note by Arron Kau
3 years, 1 month ago