Math & Scientific Calculators

About these calculators

Four tools handle everyday number work. Percentage Calculator finds what a given percentage of a number is, or what percentage one number is of another. Fraction Calculator adds, subtracts, multiplies or divides two fractions and gives the simplified result together with a decimal. Prime Number Checker tells you whether a whole number up to 10¹⁵ is prime and, if not, shows its smallest prime factor, and it shows the next and previous primes where they exist. LCM & GCF Calculator returns the greatest common factor and the least common multiple of two numbers.

Each tool shows its method on its own page. The LCM and GCF tool rounds any decimal you type to the nearest whole number before working, and the prime checker refuses decimals and shows only the smallest factor, not a full factorization. The fraction calculator works one pair of fractions at a time, so longer sums need two steps, and mixed numbers have to be written as improper fractions first. None of these tools shows step-by-step working. All calculations are done in your browser. The prime checker also explains on screen why 0, 1 and negative numbers are not prime. The greatest common factor is what you divide by to reduce a fraction, and the least common multiple gives a common denominator, so the fraction and LCM & GCF tools are often used together. For trigonometry, logarithms, factorials and quadratic equations, see the Scientific category.