What the board asks
We went through the ISC board papers, question by question, and matched each question to a topic. Here is what was asked, how often, and what was never asked.
Computer Science: 180 topics in the 2027 syllabus, across 10 units. The board has asked 117 of them at least once. 63 were never asked in the papers we checked.
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CS7 Recursion
All the topics in Computer Science: Recursion
Asked topics first, the most asked at the top. Tap a topic to see what to write, the result, the years, and the real board questions.
15 topics shown
| # | Topic | Type | Marks | Times asked | Last asked | Status |
|---|---|---|---|---|---|---|
| 1 | State what a recursive method does apart from recursionName in one line the task the traced method performs (for example GCD, maximum of an array, sum of even elements, decimal to hexadecimal, square root of a perfect square), using the dry run values as evidence. | Give reason | 1 | 5 papers | 2026 | Asked |
| 2 | Design a class with a recursive digit methodWrite the class with the data members given, the constructor, accept(), the recursive method on the digits (reverse, sum of digits, digit power sum, count of a digit, eventual digit sum, ending-digit check) with base case and no loop, the checking or display method that calls it and prints the message, and main() that creates the object and calls the methods. | Program | 8 | 5 papers | 2026 | Asked |
| 3 | Output of a recursive method on an integer (dry run)Write the chain of calls with the value of each argument down to the base case, then the values returned back up, and give the final returned value for each input asked. | Dry run / output | 2 | 5 papers | 2025 | Asked |
| 4 | Output of a recursive base conversion method (dry run)Trace each call with n, the remainder and the digit or character it gives, then build the result in the right order as the calls return, and give the final number or string. | Dry run / output | 2 | 2 papers | 2026 | Asked |
| 5 | Output of a recursive method on an array (dry run)Make a table of each call with the index and any carried value (max, sum), follow it until the base case, and give the returned value. | Dry run / output | 2 | 2 papers | 2025 improvement | Asked |
| 6 | Differences between iteration and recursionState two clear differences, each as a matched pair (recursion ... whereas iteration ...), for example self-call versus loop, base case versus loop condition, extra stack memory and call overhead versus none. | Comparison | 2 | 1 paper | 2026 | Asked |
| 7 | Recursion and the call stack: LIFO, missing base caseExplain that each call is pushed on the system stack and returns in last-in-first-out order, and that a missing or unreachable base case gives endless calls (infinite recursion, StackOverflowError); answer the assertion-reason form on this. | Give reason | 1 | 1 paper | 2024 | Asked |
| 8 | Design a class that converts number bases recursivelyWrite the class with the number and result members, the constructor, the input method, the recursive convert method (decimal to binary, octal or hexadecimal, or the reverse) that builds the result in the right digit order, the display method that calls it, and main(). | Program | 8 | 1 paper | 2024 | Asked |
| 9 | Design a class with recursive binary search on an arrayWrite the class with the array and size, the constructor, the fill method, a standard sort into ascending order, the recursive binary search bin_search(l, u, v) returning the index or -1, and main() that fills, sorts, searches and prints the result. | Program | 8 | 1 paper | 2020 | Asked |
| 10 | Design a class with a recursive factor or GCD methodWrite the class with the data members given, the constructor, the recursive method that runs a divisor i through the range (sum of factors, count of factors, prime test, GCD or LCM) with its base case, the check method that calls it with the right starting argument and prints the result, and main(). | Program | 8 | 1 paper | 2018 | Asked |
| 11 | Define recursion, base case and recursive caseWrite that a recursive method calls itself on a smaller version of the same problem, name the base case (the stopping condition with a known answer) and the recursive case (the self-call that moves towards the base case), and point them out in a short given method. | Statement | 1 | never | Never asked | |
| 12 | Write the recursive equation for a functionWrite the base case and the recurrence for a function stated in words (factorial, power, Fibonacci, GCD, sum of digits, count of digits, nCr) in the form f(n) = value if condition, else expression in f(smaller). | Sum | 2 | never | Never asked | |
| 13 | Write a short recursive method from its definitionWrite the Java method header exactly as given, the base case with its return value, and the recursive return statement, for a standard function such as factorial, power, Fibonacci, GCD, sum or count of digits, reverse of a number. | Program | 3 | never | Never asked | |
| 14 | Tower of Hanoi: recursive method and list of movesWrite the recursive method hanoi(n, from, via, to) with its base case, and list in order every move it makes for n = 3 (seven moves), stating the total moves 2^n - 1. | Dry run / output | 2 | never | Never asked | |
| 15 | Design a class with a recursive string methodWrite the class with the string member, the constructor and input method, the recursive method on the string (reverse, palindrome check, count of vowels or a character, word or character removal) using charAt and substring with a base case on length or index, the method that calls it and prints the result, and main(). | Program | 8 | never | Never asked |
This list was made from the 2027 syllabus and checked with 9 board papers, including the 2027 specimen paper. It is not yet checked with the textbook.
The 10 topics Computer Science papers ask most
Counted on the board papers from 2018 to the 2027 specimen paper, which every unit has been checked against.
- 1.Principle of duality: state it and write the dualCS1 Boolean Algebra · asked 8 times since 2018
- 2.Complement of an expression using De Morgan's theoremCS1 Boolean Algebra · asked 8 times since 2018
- 3.Word problem to truth table and SOP or POSCS1 Boolean Algebra · asked 8 times since 2018
- 4.K-map reduction of a four-variable POS expressionCS1 Boolean Algebra · asked 8 times since 2018
- 5.Pre-order, in-order and post-order traversalCS9 Data Structures · asked 8 times since 2018
- 6.K-map reduction of a four-variable SOP expressionCS1 Boolean Algebra · asked 7 times since 2018
- 7.Read a tree: leaves, internal nodes, parent, siblings, degreeCS9 Data Structures · asked 7 times since 2018
- 8.Truth table to classify tautology, contradiction or contingencyCS1 Boolean Algebra · asked 6 times since 2018
- 9.Convert between cardinal and canonical formsCS1 Boolean Algebra · asked 6 times since 2018
- 10.Address of an element, row major and column majorCS6 Arrays and Strings · asked 6 times since 2018