| \( a\times 5 \) | \( a/2\times10 \) |
| \( a\times 6 \) | \( a\times2\times3 = a + a\times5 \) |
| \( a\times 7 \) | \( a\times2 + a\times5 = a/3 \times (20+1)\) |
| \( a\times 8 \) | \( a\times3 + a\times5 = a\times10 - a\times2 \) |
| \( a\times 9 \) | \( a\times10 - a \) |
| \( a\times11 \) | 从右向左累加 |
| \( a\times12 \) | \(a\times10+a\times2\) |
| \( a\times13 \) | \(a\times10+a\times3\) |
| \( a\times14 \) | \(a\times7\times2\) |
| \( a\times15 \) | \(a\times30/2\) |
| \( a\times16 \) | \(a\times8\times2\) |
| \( a\times17 \) | \(a\times10 + a\times7 = a/3 + a/3/2\times100 \) |
| \( a\times18 \) | \(a\times9\times2\) |
| \( a\times19 \) | \(a\times20 - a\) |
| \( a\times21 \) | \(a\times20 + a\) |
| \( a\times22 \) | \(a\times11\times2\) |
| \( a\times25 \) | \(a\times100/4\) |
| \( a\times33 \) | 略小于\(a\times100/3\) |
| \( a/7 \) | 约等于 \(a\times 3/20\times(1 - 1/20)\) |
| \( a/9 \) | 约等于 \(a\times 0.11\) |
| \( a/17 \) | 约等于 \(a\times 6/100\times(1-0.02)\) |