Chapter 12 - Exponential Functions and Logarithmic Functions - 12.1 Composite Functions and Inverse Functions - 12.1 Exercise Set - Page 788: 82

$6.3\times 10^{-15}$

Multiply the decimal numbers separately, and powers of ten separately. $1.5\times 4.2 =6.3$ (this is between 1 and 10, and is what we want for scientific notation) $10^{-3}\times 10^{-12}=10^{-3+(-12)}=10^{-15}$ $=6.3\times 10^{-15}$