How to Run a Fair Random Selection
Plan a fair informal random selection by defining eligibility, entries, draw rules, redraws, privacy safeguards, and records before choosing a result.
Number toolsHow to Pick Random Numbers From a Custom List
Use a custom numeric list to pick one or more unique values, including nonconsecutive numbers, decimals, zero, and negatives.
Online securityHow to Create a Strong Random Password
Learn how password length, randomness, unique credentials, and secure storage work together to protect online accounts.
FractionsHow to Calculate Fractions
Learn exact fraction arithmetic, simplification, mixed numbers, and practical ways to check each result.
RatiosHow to Simplify Ratios and Solve Proportions
Understand ratio order, equivalent ratios, scaling, units, and exact missing-term calculations.
Factors and multiplesHow to Find the Greatest Common Factor
Learn factor lists, the Euclidean algorithm, prime factorization, and practical ways to verify a GCF.
Factors and multiplesHow to Find the Least Common Multiple
Learn multiple lists, prime factorization, the GCF relationship, and exact multi-number LCM methods.
DecimalsHow to Add, Subtract, Multiply, and Divide Decimals
Learn decimal place value and reliable methods for addition, subtraction, multiplication, and division, including exact fractions and repeating results.
RatiosHow to Solve a Proportion Using Cross-Multiplication
Solve any missing term in a proportion with exact cross-products while respecting denominator, sign, unit, and model requirements.
Number theoryHow to Check Whether a Number Is Prime
Test integer candidates with definitions, divisibility checks, the square-root bound, and the Prime Number Checker's deterministic 64-bit method.