remember that scientifc notation is always (number greater than or equal to 1 and less than 10) times 10^(number of decimal places moved to the right)
ok so remember htat whe multiplying you can assosiat the numbesr so we have (6.5)(10^-7)(4)(10^-4)=(6.5 times 4)(10^-7 times 10^-4)
also remember the exponential law that says
x^m times x^n=x^(m+n) so
10^-7 times 10^-4=10^(-7+-4)=10^-11
so now we have
6.5 times 4 times 10^-11
26 times 10^-11
26 needs to be more than 1 and less than 10
2.6 times 10^1 times 10^-11
combine the 10's
10^1 times 10^-11=10^(1+-11)=10^-10
2.6 times 10^-10
answer is 2.6 times 10^-10