What is 0.4 percent of 128 - step by step solution

To get the solution, we are looking for, we need to point out what we know.

1. We assume, that the number 128 is 100% - because it's the output value of the task.
2. We assume, that x is the value we are looking for.
3. If 128 is 100%, so we can write it down as 128=100%.
4. We know, that x is 0.4% of the output value, so we can write it down as x=0.4%.
5. Now we have two simple equations:
1) 128=100%
2) x=0.4%
where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that:
128/x=100%/0.4%
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for what is 0.4% of 128

128/x=100/0.4
(128/x)*x=(100/0.4)*x       - we multiply both sides of the equation by x
128=250*x       - we divide both sides of the equation by (250) to get x
128/250=x
0.512=x
x=0.512

now we have:
0.4% of 128=0.512