| ( | a | × | 1 5 | + | a | ) | × | 1 5 | + | ( | a | × | 1 5 | ) | + | a | + | ( | ( | a | × | 1 5 | + | a | ) | × | 1 5 | + | ( | a | × | 1 5 | ) | + | a | ) | × | 3 5 | = | 181260 |
| 方程左边 = | a | × | 1 5 | × | 1 5 | + | a | × | 1 5 | + | ( | a | × | 1 5 | ) | + | a | + | ( | ( | a | × | 1 5 | + | a | ) | × | 1 5 | + | ( | a | × | 1 5 | ) | + | a | ) | × | 3 5 |
| = | a | × | 1 25 | + | a | × | 1 5 | + | ( | a | × | 1 5 | ) | + | a | + | ( | ( | a | × | 1 5 | + | a | ) | × | 1 5 | + | ( | a | × | 1 5 | ) | + | a | ) | × | 3 5 |
| = | 31 25 | a | + | ( | a | × | 1 5 | ) | + | ( | ( | a | × | 1 5 | + | a | ) | × | 1 5 | + | ( | a | × | 1 5 | ) | + | a | ) | × | 3 5 |
| = | 31 25 | a | + | a | × | 1 5 | + | ( | ( | a | × | 1 5 | + | a | ) | × | 1 5 | + | ( | a | × | 1 5 | ) | + | a | ) | × | 3 5 |
| = | 36 25 | a | + | ( | ( | a | × | 1 5 | + | a | ) | × | 1 5 | + | ( | a | × | 1 5 | ) | + | a | ) | × | 3 5 |
| = | 36 25 | a | + | ( | a | × | 1 5 | + | a | ) | × | 1 5 | × | 3 5 | + | ( | a | × | 1 5 | ) | × | 3 5 | + | a | × | 3 5 |
| = | 36 25 | a | + | ( | a | × | 1 5 | + | a | ) | × | 3 25 | + | ( | a | × | 1 5 | ) | × | 3 5 | + | a | × | 3 5 |
| = | 51 25 | a | + | ( | a | × | 1 5 | + | a | ) | × | 3 25 | + | ( | a | × | 1 5 | ) | × | 3 5 |
| = | 51 25 | a | + | a | × | 1 5 | × | 3 25 | + | a | × | 3 25 | + | ( | a | × | 1 5 | ) | × | 3 5 |
| = | 51 25 | a | + | a | × | 3 125 | + | a | × | 3 25 | + | ( | a | × | 1 5 | ) | × | 3 5 |
| = | 273 125 | a | + | ( | a | × | 1 5 | ) | × | 3 5 |
| = | 273 125 | a | + | a | × | 1 5 | × | 3 5 |
| = | 273 125 | a | + | a | × | 3 25 |
| = | 288 125 | a |
288 125 | a | = | 181260 |
| a | = | 181260 | ÷ | 288 125 |
| = | 181260 | × | 125 288 |
| = | 5035 | × | 125 8 |
| a | = | 629375 8 |
| a | = | 78671.875 |