Negative numbers are real numbers. The set of real numbers includes all the numbers that can be shown on a number line including both positive and negative numbers. More »

Pi is a real number, as all numbers that exist on a number line are real. Real numbers include all rational and irrational numbers; pi is defined as an irrational number. More »

A non-real, or imaginary, number is any number that, when multiplied by itself, produces a negative number. Mathematicians use the letter "i" to symbolize the square root of -1. An imaginary number is any real number mul... More »

When adding numbers, the rules of significant figures dictate that the sum should be rounded to the same place as the least significant place of the number, with the least number of places after the decimal point. Signif... More »

The numbers between 30 and 40 whose only factors are one and themselves, also called prime numbers, are 31 and 37. Prime numbers are useful in generating numerical passwords or codes that are difficult to crack. More »

A Roman numeral conversion chart allows the translation of numbers from Roman symbols to the Arabic figures used worldwide. The Cincinnati City School System ABLE/GED program provides such a chart, detailing the Roman sy... More »

To add decimals, first write down the numbers, one below the other, with the decimal points in line with each other. If the numbers have different numbers of digits, add zeros to shorter numbers to equalize the length. T... More »