How to Calculate Two Thirds of a Number

By Sky Smith
You may need a calculator to assist with your math.

Fractions generally represent a portion of something. For instance, if 75 percent of 1,000 students passed a math course, then you could say that 75 out of 100, or three-fourths, of every student passed the course. By applying this fraction, three-fourths, to the whole number, 1,000, you can find exactly how many students passed the course. In this case, three-fourths (3/4) equals 0.75, which when multiplied to 1,000 yields 750. Needless to say, converting fractions to decimals is just one of many ways to handle fractions and other numbers.

By Calculator

Type in two divided by three and press the equals sign on your calculator. You should receive a decimal similar to 0.666… repeating.

Press the multiplication sign and type in the number of interest. For example, if you are finding two-thirds of 100, after you press multiplication sign type in "100." Then press the equals sign.

Interpret your result. If you have 66.666… repeating, then you may wish to round this to the tenths place of 66.7. Thus, two-thirds of 100 is approximately 66.7.

By Hand

Divide the number of interest by 3. If you are finding two-thirds of 60, then first divide 60 by 3. You will get the number 20 as your result.

Round your result to the tenths place. In some cases, you may get a repeating decimal and it may be easier to use a smaller approximation. For instance, if you divide 250 by 3 you get 83.333... repeating. You may want to use 83.3 as your result instead of the entire decimal.

Multiply the result by 2. If you have 20 as your result, then 20 times two is 40. Therefore, two-thirds of 60 is 40.


You can also multiply by two first and then divide your result by three, when calculating two-thirds by hand.

About the Author

Sky Smith has been writing on psychology, electronics, health and fitness since 2002 for various online publications. He graduated from the University of Florida with honors in 2005, earning a Bachelor of Science in psychology and statistics with a minor in math.