The following is a riddle that used to make rounds on the internet: I have 50, then I spend it in the following way.
| Spend | Balance |
| 20 | 30 |
| 15 | 15 |
| 9 | 6 |
| 6 | 0 |
| Total spend = 50 | Total balance = 51 |
The total spend is 50, and the total balance is 51 – how to explain the extra 1?
The riddle has intrigued a lot of people. But the answer is: no rule requires matching the sum of spend with the sum of the balance! Take this extreme example: I have 50, and I spent it fully.
| Spend | Balance |
| 50 | 0 |
| Total spend = 50 | Total balance = 0 |
This time there is not much effort required for the mind to get convinced.
