Prime Number: Your Questions Answered
These are the questions people ask most often about prime number. Each answer is short; follow the links for the full detail.
What does a prime number calculation tell me?
Checks whether a number is prime.
What is the formula?
Test divisors up to √n.
What do I need to enter?
Whole number.
Can I use any units?
Yes, as long as every input uses the same unit. The answer will be in that unit (squared for areas, cubed for volumes).
Can you show an example?
For example, with these inputs:
- Whole number: 97
the calculator returns:
- Result: 97 is a prime number
Any tips?
- Write down the formula before plugging numbers in; it prevents mixing up variables.
- When numbers are very large or small, scientific notation makes them easier to compare.
- Check your answer by working backwards from the result.
Background
These calculations appear throughout the Singapore syllabus, from primary school percentages and fractions to secondary school algebra and geometry. Understanding the formula makes problem sums easier because you can recognise which quantity is missing.
Calculators are best used to check working rather than replace it, especially for exams where method marks count. Work the problem by hand first, then confirm with the calculator.
A quick mental estimate before calculating is a powerful check. If a room's floor area comes out at 4,000 square metres or a percentage comes out above 100% when it should not, you know to look again.
Related calculations
- Rounding Calculator: Rounds a number to the decimal places you choose.
- Number to Words Converter: Writes numbers in English words, handy for cheques.
- Roman Numeral Converter: Converts numbers to Roman numerals.
- Decimal to Binary Converter: Converts a base-10 number to binary, octal and hex.
Try it yourself with the Prime Number Checker.
Run your own numbers: Prime Number Checker