Everyone needs to know their income. Whether you are filling out a loan application or considering a job offer, it is important to know your monthly and annual income. Let's say, for example, you just started a new job as a salesman with a monthly base salary plus a percent bonus. To figure out your base salary plus bonus you convert the bonus percent to a decimal by dividing by 100, then calculate the amount of your bonus by multiplying the bonus converted to decimal by the base salary, and finally add the bonus to the base salary.

Assume, for example, you earn a 20 percent bonus for meeting sales goals and you met the goals every month of the year. Convert the 20 percent bonus to a decimal by dividing 20 by 100 to get .20.

Assume, for example, your base salary is $3,000 per month. Determine the amount of your bonus by multiplying $3,000 times .20 to get $600.

Add your bonus to your base salary to determine your monthly total salary including bonus -- $600 plus $3,000 equals $3,600.

Determine your annual total salary including bonus by multiplying your monthly total salary by 12 -- $3,600 times 12 equals $43,200.