Micro‑Lab: Prove Your Friend Wrong — Ethereum as a Replicated Computer

Your mathematically‑challenged friend claims it’s impossible to reach a large target value from x = 1 using his tiny contract. He deployed a minimalist “ArithmeticProxy” contract that exposes only a few calls. Each call changes a single storage variable x and costs gas.
Your challenge: from the same start state on every node, craft the lowest‑gas call sequence that lands exactly on x = target. Honest Ethereum nodes must deterministically compute the same result — any divergent node is rejected by consensus.

1) Configure the Challenge

Starts at 1. Use x = 1 to reset (expensive).
5

2) Contract Calls

Click to append calls to your “transaction.” Each has a gas cost. Because gcd(5,4)=1, the ±{5,4} pair lets you synthesize any integer.

Tip: x = 1 is costly but can reset your path.

3) Your Call Sequence

Total Gas
0
Fee (gwei)
0
Fee (ETH)
0
Friend’s Bet Budget (gwei)
—
Bet status: —
Consensus Result: Determinism check across all nodes
— not executed yet —
Goal: Prove your friend wrong by hitting x = target with minimum gas — and beat their bet budget.

4) Simulated Nodes

Each node independently executes the same call sequence. Honest nodes must match exactly. A faulty node (if injected) will diverge and be rejected.

What is this showing?

Ethereum is a replicated state machine: given the same input (start state, call sequence, gas), all honest nodes compute the same output. The network reaches consensus on that output and rejects any divergent computation.

Hotkeys: R run, U undo, C clear, D demo. © Micro‑Lab | CC‑BY for classroom use