Suppose that we modified cc-check so that, instead of adding the ones digit and (if it exists) the tens digit to sum in Line 7 of the algorithm, we instead simply added the ones digit. (That is,...

Suppose that we modified cc-check so that, instead of adding the ones digit and (if it exists) the tens digit to sum in Line 7 of the algorithm, we instead simply added the ones digit. (That is, replace Line 7 by sum := sum + di .) Does this modified code still allow us to detect any single substitution error?