20 times 20 is 400. In symbols: 20 × 20 = 400 (20 squared).
20 × 20 means adding 20 to itself 20 times: that is 20 copies of 20, which add up to 400.
20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, ... (keep going to the 20th multiple). The 20th multiple of 20 is 400.
20 × 20 = 20 × 20 = 400 = 400.
Halve one number and double the other: 20 × 20 = 10 × 40 = 400.
400 ÷ 20 = 20
400 is even and a perfect square. Prime factorization: 2 × 2 × 2 × 2 × 5 × 5.
| Multiplication | Answer |
|---|---|
| 19 × 20 | 380 |
| 20 × 21 | 420 |
| 20 × 22 | 440 |
| 18 × 20 | 360 |
See also: factors of 400 · 20 squared.
Other numbers? Browse the multiplication table, the squares and cubes or the exponent calculator.