| Question | Select the number from among the given options that can replace the question mark (?) in the following series. 18, 3, 36, 6, 54, 9, ? | |
| Type | multiple_choice | |
| Option | 89 | incorrect |
| Option | 90 | incorrect |
| Option | 12 | incorrect |
| Option | 72 | correct |
| Solution | 18, 18 + 18 = 36, 36 + 18 = 54, 54 + 18 = 72 18, 3, 36, 6, 54, 9, 72 | |
