11 times 21 is 231. In symbols: 11 × 21 = 231, and 21 × 11 = 231 too.
11 × 21 means adding 11 to itself 21 times: that is 21 copies of 11, which add up to 231.
11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 121, 132, ... (keep going to the 21th multiple). The 21th multiple of 11 is 231.
11 × 21 = 11 × 20 + 11 × 1 = 220 + 11 = 231.
231 ÷ 11 = 21
231 ÷ 21 = 11
231 is odd. Prime factorization: 3 × 7 × 11.
| Multiplication | Answer |
|---|---|
| 10 × 21 | 210 |
| 12 × 21 | 252 |
| 11 × 20 | 220 |
| 11 × 22 | 242 |
| 11 × 23 | 253 |
| 11 × 19 | 209 |
| 13 × 21 | 273 |
| 9 × 21 | 189 |
Other numbers? Browse the multiplication table, the squares and cubes or the exponent calculator.