Skip to main content
← Back to archive

Problem #56 · September 21, 2026

Natural numbers

When the first 2525 natural numbers are written out, how many times does the digit 22 appear?
  1. A99
  2. B88
  3. C66
  4. D1010

WORKED EXAMPLE

Solution

In the ones place, the digit 22 appears in the numbers 2,12,222, 12, 22 — 33 times; in the tens place, it appears in the numbers 20,21,22,23,24,2520, 21, 22, 23, 24, 25 — 66 times. In total, 3+6=93+6=9 times.
Solve today's problem