Maths & Science

Free maths calculators for homework, work and everyday sums: fractions, averages, LCM and GCF, scientific notation and more, with the working shown.

Maths calculators show the working, not just the answer, so you can check homework, a spreadsheet or a quick sum at work. Students in the UK and the US use them for revision, parents use them to help with homework, and people at work use them to check a figure before it goes in a report.

The LCM Calculator and the GCF Calculator (GCD and HCF) take two or more whole numbers and show the method two ways: by prime factorisation and by Euclid's algorithm. The LCM of 12 and 18 is 36 and their greatest common factor is 6. UK schools usually call the second one the highest common factor, US schools say GCF, and programmers say GCD; all three are the same number.

The Fraction Calculator adds, subtracts, multiplies and divides fractions and mixed numbers, then gives the result as a simplified fraction, a mixed number, a decimal and a percentage, so 1 1/2 + 2 3/4 comes out as 4 1/4 or 4.25. The Average Calculator finds the mean, median, mode, range, count and sum of up to 10,000 values, with an optional weighted average, and treats values as exact fractions so long lists do not drift.

The Scientific Notation Calculator converts to and from scientific, E and engineering notation, rounds to significant figures and shows each step of adding, subtracting, multiplying or dividing. In the UK, standard form means 4.5 × 10⁴; in the US, standard form usually means the ordinary number 45,000, and the tool gives both. The Midpoint Calculator works in 2D and 3D and also gives the distance and gradient between the points, or a missing endpoint. The Percent Error Calculator compares a measured value with the true one, with absolute, relative and signed error for science practicals.

Everything runs in your browser. The working follows common textbook methods, so check how your teacher wants it set out.

  • LCM Calculator

    Find the lowest common multiple of two or more whole numbers, with the working shown by prime factorisation and by the GCD method.

  • GCF Calculator (GCD and HCF)

    Find the greatest common factor (GCF), also called the GCD or HCF, of two or more whole numbers with Euclid's algorithm and prime factors.

  • Average Calculator

    Paste a list of numbers to get the mean, median, mode, range, count and sum, with the working, plus an optional weighted average.

  • Fraction Calculator

    Add, subtract, multiply and divide fractions and mixed numbers, then simplify and convert the answer to a mixed number, decimal and percentage.

  • Scientific Notation Calculator

    Convert numbers to and from scientific, E and engineering notation, round to significant figures, and add, subtract, multiply or divide with steps.

  • Midpoint Calculator

    Find the midpoint between two points in 2D or 3D, the distance between them and the gradient, or find a missing endpoint, with the working.

  • Percent Error Calculator

    Work out the percent error between a measured value and the true value, with absolute and relative error, a signed option and the working.

Common questions about maths & science

What is the LCM of 12 and 18?

36. The prime factors are 2² × 3 for 12 and 2 × 3² for 18, and the LCM takes the highest power of each prime: 2² × 3² = 36. The GCF of the same pair is 6, and 12 × 18 ÷ 6 also gives 36. The LCM Calculator shows both methods.

What is 1 1/2 plus 2 3/4?

4 1/4. Convert both to improper fractions over a common denominator of 4: 6/4 + 11/4 = 17/4, which is 4 1/4 or 4.25 as a decimal. The Fraction Calculator shows each of these steps and simplifies the answer for you.

Is standard form the same as scientific notation?

In the UK, yes: standard form means writing 45,000 as 4.5 × 10⁴. In the US, standard form usually means the ordinary number, 45,000, so check which one your course means. The Scientific Notation Calculator gives both, along with E notation and engineering notation.

What is the difference between mean, median and mode?

The mean is the total divided by the count, the median is the middle value in order, and the mode is the most common value. For 6, 3, 9, 6, 2 and 8 the mean is 5.67, the median is 6 and the mode is 6. The Average Calculator gives all three with the working.

What is the formula for percent error?

Percent error is the size of the difference between the measured and true values, divided by the true value, times 100. Measuring 52 when the true value is 50 gives an error of 2, and 2 ÷ 50 × 100 = 4%. The Percent Error Calculator also shows a signed version for courses that use one.