Add a single digit to any 3-digit number (no help)
Add a single digit to a 3-digit number crossing the tens boundary.
Add a single digit to any 3-digit number (no help)
Add a single digit to a 3-digit number crossing the tens boundary.
Add a single digit to a 3-digit number crossing the tens boundary.
Add a single digit to a 3-digit number crossing the tens boundary.