Answer
$420 \times 10^{11} = 4.2 \times 10^{13}$
Work Step by Step
Move the decimal point two places to the left to get $4.2$.
Then, multiply by $10^{2}$ (or increase the exponent of 10 by 2) to retain the original value.
$420 \times 10^{11} = 4.20 \times 10^{11+2}=4.2 \times 10^{13}$
