College Algebra (6th Edition)

$2.15$ x $10^{20}$
Human brain: $3$ x $10^{10}$ neurons Gorilla brain: $7.5$ x $10^{9}$ neurons Combine the coefficients and exponents. Then add $1$ to the exponent since scientific notation will put the decimal point one more place to the left. $3$ x $10^{10}$ x $7.5$ x $10^9$ $21.5$ x $10^{19}$ $2.15$ x $10^{20}$