If you know a lot about chemistry, or are in the process of learning it (such as in a Physical Science course, or in an actual chemistry class), you will have to learn how to balance equations. You must do this to conform to the Law of Conservation of Mass, which states that mass cannot be created nor destroyed. An unbalanced equation is when the number of atoms on both sides of the equation are not the same. You must balance an equation using coefficients to make everything equal.
You can always write an equation on paper and balance it by hand, but there is now another way you can balance an equation, and this time it involves the internet. While browsing the internet for chemical equations and other topics, I ran into this online tool. The site allows you to balance an equation by typing it in. In my tests it has been fairly accurate.
To balance an equation, enter an equation into the box. Where there is subscripts, just type the numbers. The tool automatically interprets the numbers as subscripts. When done, press enter or click "Balance!". The page should update with the balanced equation, and it should give you a link to the specific chemical equation.
So as an example, I balanced this equation. Here is an image below.
You can take a spin of the website by clicking here. Hope you all find this as a valuable resource. However, I always recommend you double check. I have never came across an issue with it giving false answers, but I'm just leaving that out there for those who think that they can just heavily rely on this tool.