5 times 21 is 105. In symbols: 5 × 21 = 105, and 21 × 5 = 105 too.
5 × 21 means adding 5 to itself 21 times: that is 21 copies of 5, which add up to 105.
5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ... (keep going to the 21th multiple). The 21th multiple of 5 is 105.
5 × 21 = 5 × 20 + 5 × 1 = 100 + 5 = 105.
105 ÷ 5 = 21
105 ÷ 21 = 5
105 is odd. Prime factorization: 3 × 5 × 7.
| Multiplication | Answer |
|---|---|
| 4 × 21 | 84 |
| 6 × 21 | 126 |
| 5 × 20 | 100 |
| 5 × 22 | 110 |
| 5 × 23 | 115 |
| 5 × 19 | 95 |
| 7 × 21 | 147 |
| 3 × 21 | 63 |
See also: factors of 105.
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