1. ## A little help please

ok well i have to take placement tests for college in a month, and its been 2 years since high school, so im a bit rusty and could use some help

ok so heres the problem, i need it explained how to do it

(2.3 x 10^4)(3 x 10^-2)
----------------------
5 x 10^-6

ok so if u can understand how i wrote that, top is divided by bottom, any help on this please, kinda detailed

2. Originally Posted by PhilL
ok well i have to take placement tests for college in a month, and its been 2 years since high school, so im a bit rusty and could use some help

ok so heres the problem, i need it explained how to do it

(2.3 x 10^4)(3 x 10^-2)
----------------------
5 x 10^-6

ok so if u can understand how i wrote that, top is divided by bottom, any help on this please, kinda detailed
remember that multiplication is commutative, so we can multiply in whatever order we feel like, let's choose a convenient one.

recall that when we multiply numbers of the same base, we add the powers, when we divide numbers of the same base, we subtract the power from the base in the denominator from the one in the numerator. let's see how all this works out:

(2.3 x 10^4)(3 x 10^-2)..........2.3 x 3 x 10^4 x 10^-2
------------------------..=..-------------------------- ..reorder the terms
.......5 x 10^-6..............................5 x 10^-6

...........................................6.9 x (10^(4-2))
....................................=..-------------------- .....add the powers of 10
.............................................5 x 10^-6

...........................................6.9 x 10^2
....................................=..---------------
.............................................5 x 10^-6

.........................................6.9..........10^2
....................................=..-----..x..--------- ..separate terms
..........................................5...........10^-6

....................................= 1.38 x 10^(2-(-6)) ...subtract powers of 10

....................................= 1.38 x 10^8