Ethereum Developer Cheat Sheet 2026

The 30 highest-yield Ethereum Developer facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Use of assert is to... → Examine user input arguments
2. What is the purpose of the `SELFDESTRUCT` opcode in Solidity (pre-Cancun)? → To destroy the contract and send its remaining ETH balance to a specified address
3. Variables of the type address hold → A value of 20 bytes
4. What major change did the Ethereum Merge (2022) introduce? → Replaced Proof of Work with Proof of Stake consensus
5. It is best to use the blockchain to its full potential... → To only utilize it for purposes that require the advantages of the blockchain.
6. Which Solidity keyword is used to declare a function that cannot modify contract state? → view
7. What does it mean when we say, "A Hashing Algorithm is deterministic"? → When given the same input, it always generates the same output.
8. What is the unit `Wei` in Ethereum? → The smallest denomination of Ether (1 ETH = 10^18 Wei)
9. What is the primary function of the Ethereum Virtual Machine (EVM)? → To execute smart contract bytecode in a sandboxed environment
10. In Ethereum's EIP-1559 fee model, what is the 'priority fee' (tip)? → An optional fee paid directly to validators to incentivize faster inclusion
11. What is the maximum stack depth of the EVM? → 1024 items
12. The result of the division of two integers, 5/2, is → 2, as the decimal point has been truncated.
13. What is a Signer in ethers.js? → An abstraction that holds a private key and can sign and send transactions
14. How much ETH was generated from 1 BTC at the start of the Ethereum token sale? → 2000 ETH
15. The ETH2 mascot was given the name of : → Leslie Lamport
16. What is a stablecoin in the Ethereum ecosystem? → A token designed to maintain a stable value, usually pegged to a fiat currency like USD
17. What does `eth_call` do in contrast to `eth_sendTransaction`? → eth_call simulates a call without modifying state; eth_sendTransaction writes to the chain
18. Which Solidity function is called when Ether is sent to a contract with no calldata? → receive()
19. What address will be in msg.sender in Contract B if a User calls Contract A and that calls Contract B? → Contract A
20. What is the difference between `memory` and `storage` in Solidity? → memory is temporary and wiped after execution; storage persists on-chain
21. What is a Solidity `modifier` used for? → Reusing pre- and post-condition logic across multiple functions
22. How much gas does a standard ETH transfer (no data, no contract) cost? → 21,000 gas
23. If you require more precise functionality than what solidity provides by default → Inline-assembly can be used to improve controls.
24. Which Solidity keyword marks a state variable as unchangeable after deployment? → immutable
25. What is the role of an oracle in a DeFi smart contract? → To provide off-chain real-world data (like prices) to smart contracts on-chain
26. Which eth2 client launched the first testnet that allowed community participation before anyone else? → Nimbus
27. Why can using `uint8` for local variables cost MORE gas than `uint256` in Solidity? → The EVM's 256-bit word size requires extra masking operations when using smaller types
28. What is MetaMask's primary role in a browser-based dApp? → An injected wallet that provides a Web3 provider and Signer to the dApp
29. Which network node is not PoW? → Rinkeby
30. What is a Provider in the context of ethers.js? → A read-only connection to an Ethereum node for querying blockchain data