The average of 12, 15, and 18 is:

**The reasoning** To find the average (or mean), you add all the numbers together, then divide by how many numbers there are. Here: 12 + 15 + 18 = 45 We have 3 numbers, so: 45 ÷ 3 = **15** The principle is simple: **Average = Sum of all values ÷ Number of values** Notice something beautiful here — 15 is actually the middle number! When numbers are evenly spaced (12, 15, 18 — each 3 apart), the average is always the middle value. **Why the wrong options tempt you** - **14** might come from adding wrong or dividing by 4 instead of 3 - **16** could happen if you miscalculated 45 ÷ 3, or added an extra number by mistake - **17** appears if you rushed and estimated badly, thinking "somewhere between 15 and 18" **Quick takeaway** Always write it out: *add everything up, count how many numbers, divide* — and when numbers are equally spaced, the average sits right in the middle!