Which of the following is the greatest number?

To compare numbers written in different forms — fractions, percentages, and decimals — convert every value into a common form (decimal), using: a fraction a/b equals a ÷ b; a percentage p% equals p ÷ 100; a number already in decimal form needs no conversion. The greatest number is whichever has the largest value after this normalization.

1. 2/8 = 2 ÷ 8 = 0.25

2. 1/2 = 1 ÷ 2 = 0.5

3. 20% = 20 ÷ 100 = 0.2

4. 0.22 is already a decimal, so it stays 0.22

Comparing the decimal forms: 0.5 > 0.25 > 0.22 > 0.2. So 1/2 (0.5) is the greatest number.

As an independent check, express every value as a fraction with the same denominator, 100: 2/8 = 25/100, 1/2 = 50/100, 20% = 20/100, 0.22 = 22/100. Comparing the numerators — 50 > 25 > 22 > 20 — confirms that 1/2 is the greatest number.