2:9=?

2:9 usually means the ratio 2 to 9. Depending on what you need:

• As a fraction: 2/9
• As a decimal: 2/9 = 0.222… (repeating)
• If you want the share of the whole (parts out of 11): first part = 2/11 ≈ 0.1818…, second part = 9/11 ≈ 0.8181…

If you meant something else, let me know the context.