| 0 | = | 90 | + | ( | n | − | 83 | ÷ | 9 | ) | ( | n | − | 8 | ) |
| 方程右边 = | 90 | + | n | ( | n | − | 8 | ) | − | 83 | ÷ | 9 | × | ( | n | − | 8 | ) |
| = | 90 | + | n | ( | n | − | 8 | ) | − | 83 9 | ( | n | − | 8 | ) |
| = | 90 | + | n | n | − | n | × | 8 | − | 83 9 | ( | n | − | 8 | ) |
| = | 90 | + | n | n | − | 8 | n | − | 83 9 | n | + | 83 9 | × | 8 |
| = | 90 | + | n | n | − | 8 | n | − | 83 9 | n | + | 664 9 |
| = | 1474 9 | + | n | n | − | 155 9 | n |
| 0 | = | 1474 9 | + | n | n | − | 155 9 | n |