Explanation: 9999 has four '9's, so the answer is 4. 8888 has four '8's, so the answer is 8. 1816 has one '1', one '8' and two '6's, so the answer is 6. 1212 has three '2's, so the answer is 0.
Therefore, 1919 has two '9's and two '1's, so the answer is 8.
The answer is 8.
Explanation:
9999 has four '9's, so the answer is 4.
8888 has four '8's, so the answer is 8.
1816 has one '1', one '8' and two '6's, so the answer is 6.
1212 has three '2's, so the answer is 0.
Therefore, 1919 has two '9's and two '1's, so the answer is 8.