AP CSA FRQ Guide
2017 FRQ 1: Digits
Build a Digits object from an integer and determine whether the stored digits are strictly increasing from left to right.
ArrayList and Number Processing22 minute targetArrayListconstructorsinteger decompositiontracing
Skills Tested
What this FRQ is really practicing
ArrayListconstructorsinteger decompositiontracing
Treat these skills as the study checklist. If any tag feels shaky, review that topic before attempting the full written response.
Starter Approach
How to begin without copying a solution
- 1Constructor: decompose the integer into digits while preserving left-to-right order.
- 2Method: compare adjacent values and return false as soon as the strict-increase rule fails.
Write a first attempt before revealing any solution outline. Most AP CSA FRQ progress comes from tracing your own code and finding the missing case.
Common Mistakes
Mistakes to watch for while writing
Storing digits backward after repeated remainder operations.
Allowing equal adjacent digits even though the prompt says strictly increasing.
Forgetting that a one-digit number is already strictly increasing.
Self Check
Review questions before you submit
Uses division or remainder to process digits.
A solution usually uses % 10 and / 10 or a string-based traversal.
Preserves the original digit order in the list.
If you peel from the right, insert at index 0 or reverse later.
Compares adjacent digit values.
Compare digit k with digit k + 1, not every pair.
Rejects equal or decreasing adjacent digits.
Strictly increasing means the next digit must be greater.
Practice Links