Arithmetic fluency
See useful products, quotients, sums and differences without repeatedly calculating from scratch.
Optiver Zap-N Assessment Tool
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Optiver's number box tests your mental maths and problem solving skills. You must perform an arithmetic operation on each number until the target number is reached. If you cannot solve the question, you can skip, however you will lose a point.
Progress
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About the assessment
About the Optiver Number Box practice tool
Number Box is one component of Optiver's wider Zap-N cognitive assessment. You are given several numbers and a target, then use arithmetic operations to combine the numbers until you reach that target. On this practice page, skipping an unsolved question costs a point, so efficient search matters alongside raw arithmetic ability.
The quickest solvers do not try every operation blindly. They work backwards from the target, notice useful factors or gaps, preserve flexible numbers for later operations and abandon paths that cannot plausibly reach the target. Repeated randomised practice is useful because the goal is to improve the method, not memorise solutions.
Task
Reach a target number
Operations
+, −, ×, ÷
Assessment
Zap-N component
Practice
Randomised problems
EverythingQuant is an independent preparation platform. This practice tool is not an official Optiver assessment and does not guarantee an interview outcome.
What you are training
Skills this practice is designed to build
Backward reasoning
Start from the target and ask which final operation would make it reachable.
Search discipline
Prioritise promising combinations instead of exploring the operation tree uniformly.
Skip judgement
Recognise when continued searching is less valuable than moving to the next problem.
How to prepare
Use the tool deliberately
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1
Solve slowly first
Focus on finding compact valid routes before caring about response speed.
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2
Work backwards
For each target, identify plausible final operations and then construct the earlier steps around them.
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3
Reuse common structures
Learn to spot useful factors, near-target differences and cancellation opportunities quickly.
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4
Add decision pressure
Once solutions are reliable, practise deciding quickly whether to continue searching or skip.
Keep preparing
Continue your Optiver preparation
Optiver preparation hub
See Number Box in the context of the wider Optiver assessment and interview process.
Optiver interview questions
Continue into the quantitative reasoning and interview questions used later in preparation.
Optiver research interview guide
Review the wider OA set, including how Zap-N and Number Box fit into Optiver preparation.
FAQ
Optiver Number Box questions
What is Optiver Number Box?
It is a numerical problem-solving game associated with the wider Zap-N cognitive assessment. You combine given numbers using arithmetic operations to reach a target.
What is the best way to get faster?
Work backwards from the target, look for factors and near-target values, and learn to reject unproductive paths early rather than trying every operation.
Is Number Box the whole Zap-N assessment?
No. Number Box is one component of the broader Zap-N cognitive assessment.
Is this an official Optiver tool?
No. EverythingQuant is an independent preparation platform and is not affiliated with Optiver.