What is 0.1 percent of 405 - 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 405 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 405 is 100%, so we can write it down as 405=100%.
4. We know, that x is 0.1% of the output value, so we can write it down as x=0.1%.
5. Now we have two simple equations:
1) 405=100%
2) x=0.1%
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:
405/x=100%/0.1%
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 0.1% of 405

405/x=100/0.1
(405/x)*x=(100/0.1)*x       - we multiply both sides of the equation by x
405=1000*x       - we divide both sides of the equation by (1000) to get x
405/1000=x
0.405=x
x=0.405

now we have:
0.1% of 405=0.405