What is 0.9 percent of 420 - 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 420 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 420 is 100%, so we can write it down as 420=100%.
4. We know, that x is 0.9% of the output value, so we can write it down as x=0.9%.
5. Now we have two simple equations:
1) 420=100%
2) x=0.9%
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:
420/x=100%/0.9%
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 0.9% of 420

420/x=100/0.9
(420/x)*x=(100/0.9)*x       - we multiply both sides of the equation by x
420=111.11111111111*x       - we divide both sides of the equation by (111.11111111111) to get x
420/111.11111111111=x
3.78=x
x=3.78

now we have:
0.9% of 420=3.78