By Pamela Martin
Apr 8, 2023 8:09 pm EST
© chameleonseye/iStock/GettyImages
Mastering fraction calculations is essential for everyday tasks—from scaling recipes to measuring DIY projects. Below you’ll find clear, expert‑approved methods to compute two‑thirds ( 2/3 ) of any number using fractions, decimals, or simple arithmetic tricks.
To get two‑thirds of a number, multiply 2/3 by the target value. If the target is a whole number, first write it as a fraction with denominator 1. Multiply the numerators and the denominators separately.
Example: 2/3 × 18 = (2 × 18)/(3 × 1) = 36/3 = 12.
When the target is a mixed number (e.g., 2 5/6), convert it to an improper fraction first:
2 5/6 = (2 × 6 + 5)/6 = 17/6.
Now apply the fractional method.
Convert 2/3 to a decimal: 2 ÷ 3 ≈ 0.666667 → 0.67 (rounded to the hundredths place).
Example: 0.67 × 21 ≈ 14.07 → 14 (rounded).
You can also compute one‑third of the number and double it:
(1/3 × x) × 2 = 2/3 × x.
Or use subtraction: x – (1/3 × x) = 2/3 × x.
Large numerators and denominators can be simplified by dividing both by their greatest common factor (GCF). For example:
24/36 → GCF = 12 → (24 ÷ 12)/(36 ÷ 12) = 2/3.
See this article for more information on finding the GCF of two numbers.
