What is 12 * 123,23
Assuming you are using a comma to represent a decimal, the answer is $ 12\times123.12 = 1478.76 $. If you didn't mean a decimal and had misplaced the comma, then the answer is $ 12\times12312 = 147876 $.
Yes, I meant that to be a decimal number. Can you provide a list of countries around the world where commas are used to indicate decimals? How did the different numerical notations develop?
Countries and regions that uses decimal commas:

1. Albania
2. Algeria
3. Andorra
4. Angola
5. Argentina
6. Armenia
7. Austria
8. Azerbaijan
9. Belarus
10. Belgium
11. Bolivia
12. Bosnia and Herzegovina
13. Brazil
14. Bulgaria
15. Cameroon
16. Canada (when using French)
17. Chile
18. Colombia
19. Costa Rica
20. Croatia
21. Cuba
22. Cyprus
23. Czech Republic
24. Denmark
25. East Timor
26. Ecuador
27. Estonia
28. Faroes
29. Finland
30. France
31. Germany
32. Georgia
33. Greece
34. Greenland
35. Hungary
36. Iceland
37. Indonesia
38. Italy
39. Kazakhstan
40. Kyrgyzstan
41. Latvia
42. Lebanon
43. Lithuania
44. Luxembourg (uses both comma and point)
45. Macau (in Portuguese text)
46. Mauritania
47. Moldova
48. Mongolia
49. Montenegro
50. Morocco
51. Mozambique
52. Namibia (uses both comma and Point)
53. The Netherlands
54. North Macedonia
55. Norway
56. Paraguay
57. Peru
58. Poland
59. Portugal
60. Romania
61. Russia
62. Serbia
63. Slovakia
64. Slovenia
65. Somalia
66. South Africa
67. Spain
68. Suriname
69. Sweden
70. Switzerland
71. Tunisia
72. Turkey
73. Turkmenistan
74. Ukraine
75. Uruguay
76. Uzbekistan
77. Venezuela
78. Vietnam
79. Zimbabwe

To indicate a decimal, a separatrix chracter (a short, roughly vertical ink stroke) between the units and tenths position became the norm among Arab mathematicians, which was the most closely approximated with a comma or full stop when typeset. The practice of choosing between the two decimal marks differs between countries; for example, in France, the full stop was already in use in printing to make Roman numerals more readable, so the comma was chosen as the decimal separation there.
Do the different numerical formats ever cause confusion? Are there any examples of situations where scientists or technicians made errors based on misunderstanding which type of notation was being used?