# all Numbers and counting articles

What is a prime number?
We explain what prime numbers are and give examples of the types of questions KS2 children might be asked to test their knowledge of prime numbers.
What are square numbers?
We explain what square numbers are and how children are taught to know square numbers plus the corresponding squares of multiples of 10. We also...
What are negative numbers?
We explain what negative numbers are and how children can be taught the concept using a number line, as well as looking at the types of questions...
What are mode, mean, median and range?
We explain the meaning of the terms mode, mean, median and range, with examples of how to find each of these from a set of numbers, as well as...
What are multiples and factors?
We explain what multiples and factors are and how children are taught to recognise multiples from Year 1 and factors from Year 5, with examples of...
What is rounding numbers?
We explain what the term 'rounding numbers' means and how children are taught to go from rounding two-digit numbers in Year 2 to rounding...
What is expanded notation?
We explain what expanded notation means, how it is taught in primary school and how it can help children with addition and multiplication...
What are mathematical investigations?
We explain what types of mathematical investigations children will carry out in primary school and give examples of complex investigations they might...
What is a calculator used for in primary school maths?
We explain how children might be taught to use a calculator for primary school maths (though the 2014 curriculum suggests their use should be minimal...
What are two-step and multi-step problems?
We explain what two-step and multi-step problems are and give examples of typical problems a child might be asked to solve in primary school (and how...