Exponents and P...

Which of the following numbers should be subtracted from
$$4.5 \times {10}^{31}$$ to get $$3 \times {10}^{31}$$?

Mark the correct answer:
Is $$4 \times {10}^8 $$ greater than $$2^2 \times {10}^8 $$?

Subtract the following numbers:
$$6.5 \times {10}^{23}$$ and $$3.2 \times {10}^{23}$$

Which of the following numbers is greatest of all?
$$2^3 \times {10}^7, 3^2 \times {10}^7$$ and $$4^2 \times {10}^7$$

Fill in the blank:
$$25 \times {10}^5$$ is ______ $$2.5 \times {10}^5$$.

Find the missing term:
$$3.1 \times {10}^{49} + 3 \times {10}^{49} = $$ $$7.2 \times {10}^{49} - ? $$

Evaluate: $$3.2 \times {10}^8 + 5.2 \times {10}^8$$

Add the following numbers:
$$6.5 \times {10}^{21}$$ and $$1.1 \times {10}^{22}$$

Which of the following numbers is least?
$$7.77 \times {10}^4 $$, $$77.7 \times {10}^4$$ and $$777 \times {10}^4$$

Choose the correct answer:
In $${4}^3$$, ______ is the base.