Predict a contract address: CREATE from deployer and nonce, or CREATE2 from deployer, salt and init code (or its hash).

The price range implied by volatility over a number of days: one and two standard deviations, from implied or historical vol.

Financial-independence number from yearly spending and a withdrawal rate, and years to reach it from savings and contributions.

Compute the 4-byte function selector and event topic0 from a Solidity signature such as transfer(address,uint256).

Expiry profit and loss for a long or short call or put: break-even, maximum gain and loss, and a payoff table.

Margin call price for shares bought on margin: your cash, the loan, the maintenance requirement and the trigger price.

Check an EVM address (Ethereum, Base, Polygon...) against its EIP-55 checksum and return the correctly checksummed form.

Dividend yield, yearly income, and yield on cost and total dividends after years of dividend growth.

Compare equal periodic buys (dollar-cost averaging) with one lump sum on the first date, over a list of prices.

Ethernet wire overhead, TCP/UDP goodput and maximum packets per second at line rate for a packet size and link speed.

Bandwidth of a VoIP call (IP and Ethernet level) for a codec and packetization time, and totals for many calls.

Propagation delay (one way and round trip) over fibre, copper or radio for a distance or two coordinates, plus serialization.

Time to transfer a file at a bandwidth (with protocol overhead), or the bandwidth or data size implied by the other two.

IPv6 prefix calculator: first and last address, size, number of /64s, the nth subnet, address type and reverse DNS zone.

Reward-to-risk ratio from entry, stop and target, the win rate needed to break even, and expectancy at your win rate.

Performance stats from period returns: average, volatility, Sharpe, Sortino, compound growth and max drawdown.

Split an IPv4 network into equal subnets, or allocate VLSM subnets from host counts (largest first) with ranges and leftovers.

TCP bandwidth-delay product, window size and scale factor needed, throughput limits from window and from packet loss (Mathis).

Compare two IPv4 or IPv6 CIDR blocks: equal, contains, contained, adjacent or disjoint, their common supernet, and test an IP.

Convert an IPv4 or IPv6 address between notations: RFC 5952 compressed, expanded, integer, hex, binary, reverse DNS, NAT64.