Express the amount that you want to find two-thirds of as a fraction. Say, for instance, that you want to find two-thirds of 43. The number 43 expressed as a fraction is 43/1.
Multiply the numerators, or top numbers, of the fractions: 43/1 x 2/3. In this example, you multiply 43 by 2 to get 86.
Multiply the denominators, or bottom numbers, of the fractions. When finding two-thirds of 43, you would multiply 3 and 1 to get 3.
Express your result as a fraction. In this example, you got 86 when you multiplied the numerators and 3 when you multiplied the denominators. Expressed as a fraction, this would be 86/3.
Reduce your fraction by dividing the numerator by the denominator. In the example problem, you would divide 86 by 3 to get 28.67, or 28 2/3.