| 1 | ÷ | ( | 1 | + | r | ) | = | 90913 100000 |
| Multiply both sides of the equation by: | ( | 1 | + | r | ) |
| 1 | = | 90913 100000 | ( | 1 | + | r | ) |
| 1 | = | 90913 100000 | × | 1 | + | 90913 100000 | r |
| 1 | = | 90913 100000 | + | 90913 100000 | r |
| - | 90913 100000 | r | = | 90913 100000 | − | 1 |
| - | 90913 100000 | r | = | - | 9087 100000 |
9087 100000 | = | 90913 100000 | r |
90913 100000 | r | = | 9087 100000 |
| r | = | 9087 100000 | ÷ | 90913 100000 |
| = | 9087 100000 | × | 100000 90913 |
| = | 9087 | × | 1 90913 |
| r | = | 9087 90913 |
| r | = | 0.099953 |