Square of 18
18 squared equals 324. Squares appear in area calculations, the Pythagorean theorem, and statistics (variance uses squared distances).
Squares obey quiet rules. Divided by 9, a square only ever leaves 0, 1, 4 or 7 — 0 here. On the last digit, squares end only in 0, 1, 4, 5, 6 or 9, and 4 fits. Between its neighbors, 289 sits 35 below and 361 sits 37 above — the square ladder widens by exactly two at every step. Double the base and the square quadruples: 36² = 1296, which is 4 × 324. Two anchors most worth memorizing in this range are 12² = 144 and 15² = 225 — the odd-step rule above is why knowing them pays off, because from any anchor the next square is one step along this page's ladder.
| Expression | Value |
|---|---|
| 18² | 324 |
Frequently asked questions
What is 18 squared?
18 squared is 324, because 18 × 18 = 324. The exponent 2 is why it is written 18².
What is 19 squared, next to 18²?
19² = 361, which is 37 more than 18² = 324. Each step up adds double the base plus one.
Where do squares show up in real problems?
Area of a square with side 18, distance in the Pythagorean theorem, and variance in statistics all use squared values.