Values, expressions, and arithmetic — Change one requirement

PART I

Warm-up

Reconnect with a useful idea before starting values, expressions, and arithmetic. In one or two sentences, describe the input, output or host boundary from the previous exercise that this lesson builds on. If you are arriving directly, skim the worked example first; there is no locked prerequisite.

A rough note is enough. You can revise it after the example.

PART II

Instruction & guided example

Change the order of operations deliberately

Discounting a subtotal before adding a fixed fee is a different policy from discounting the entire bill. With integer arithmetic, choose values whose results remain exact in this introductory exercise; detailed division and rounding policy is outside this example.

Use multiplication to model a two-times promotional credit rather than guessing a percentage API. Policy A doubles the item credit then adds a fixed 3-point welcome credit: itemCredit * 2 + 3. For itemCredit 5, this is 10 + 3 = 13. Policy B doubles both credits: (itemCredit + 3) * 2 = 16.

A requirement change should alter the grouping, not silently alter the given credit amounts. Keep the original case as a regression check and explain which term moved inside the multiplication. This reveals whether you changed a rule or merely tuned an answer.

Worked reasoning and supplied artifact

fnc promotionalCredit(itemCredit: i32) -> i32 {
    return itemCredit * 2 + 3;
}

Illustrative example from the proposed WillowScript design. The language and WUIX/WMATH/WDB/WAUDIO/WTMP services are not implemented in the supplied source. This site has no interpreter, VM or native host and does not execute or certify the snippet.

Try the guided change

Change the policy to double both credits and trace itemCredit 5 and 0 under both versions.

• Write the supplied inputs and initial state before following the example.
• Reconstruct each intermediate calculation or host decision, then compare with the worked artifact.
• Explain why the contrasting alternative fails before attempting the changed inputs in Part IV.

PART III

Take a breather

Step back after the guided example. Look away from the screen, stretch, or reread your prediction. This is an optional learning pause, not a timer or an assessment gate.

When you return, try to name the lesson’s key idea without copying its wording. If that feels difficult, return to Part II and trace one line rather than restarting the entire lesson.

PART IV

Independent practice

Project context: Snack-shop calculator. Build a small, understandable change around values, expressions, and arithmetic.

A crafting event triples a base output of 4 and then adds 2 fixed gifts. The next event triples gifts too. Write both rules and trace the change without introducing floating-point assumptions.

What to produce

Old/new formulas giving 14 and 18; a second base-output case that still distinguishes the policies.

• State the intended behavior in a sentence before editing.
• Use only source-backed syntax and the host services whose contract you have been given.
• Record a normal case and a boundary or unavailable-resource case.
• Label hand predictions separately from anything actually measured in a supplied toolchain.

Syntax colors are a reading aid, not a compiler. The line you are editing stays uncolored until you move to a different line; capitalization is never changed. Drafts stay on this browser and code is not executed.

fnc add(a: i32, b: i32) -> i32 {
    return a + b;
}
fnc main() -> i32 {
    return add(2, 3);
}

PART V

Self-check

Use this check to notice what to revisit. It does not award a private course grade, block another page or claim to verify compiled code. Every answer has a learning explanation.

You may keep exploring even if you are unsure. Use the hint, compare the trace, and revise your explanation.

PART VI

Recap & small task

Bring the idea back to the mod feature you are building. A useful recap connects the mechanism to a decision you can make in your own code.

• Change the order of operations deliberately
• Discounting a subtotal before adding a fixed fee is a different policy from discounting the entire bill. With integer arithmetic, choose values whose results remain exact in this introductory exercise; detailed division and rounding policy is outside this example.
• Separate source-backed behavior, host requirements and untested predictions.

One small recap task

Describe the rule difference without using any operator symbols.

This marks your personal practice record only. It is not a certification or an official workspace assessment.