Error Intervals Worksheet

Error intervals at a glance

Error intervals are the limits of accuracy, or upper and lower bounds, for a number that has been rounded. 

When rounding numbers or truncating numbers, it can be useful to think about the values that the number could have taken before it was rounded or truncated. For example, let’s say a number x is given as 6 to the nearest whole number. Any value greater than or equal to 5.5 would round up to 6 and any value less than 6.5 would round down to 6. Therefore the lower bound of 6, rounded to the nearest whole number, is  5.5 and the upper bound is 6.5. We can write this using inequality notation: 5.5>=x<6.5. This is the error interval for our number.

We can find error intervals for numbers that have been rounded to any degree of accuracy, including the nearest integer and any number of decimal places or significant figures. We can also find error intervals for numbers that have been truncated. It is important to carefully consider the place value of the degree of accuracy when finding error intervals.

Looking forward, students can then progress to additional number worksheets, for example an equivalent fractions & ordering fractions worksheet or simplifying fractions worksheet.

For more teaching and learning support on Number our GCSE maths lessons provide step by step support for all GCSE maths concepts.