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).
🔒 Randomly assigned & locked for this challenge.
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. Because the EVM is deterministic, every honest node lands on the exact same final state — and the network reaches consensus on it.

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