AMO · 2027 · Grades 2-3 · Self-study SET 23 Question 12

The numbers $20,21,22,\ldots,63,64$ are written together as the 90-digit number $2021222324\ldots626364$. All the odd digits are removed. How many digits remain? Remove individual digits 1, 3, 5, 7 and 9, not whole numbers that contain them.



Enter one whole number, without units.