# Accuracy

To check the accuracy of a rounded number, you need to find the largest and smallest numbers that it could have been rounded from.

Question

Q1. The number of children in a school is , correct to the nearest . What is the largest possible and smallest possible number of children in the school?

Q2. Amelia spends in the local supermarket, correct to the nearest . What is the greatest and least amount that Amelia could have spent?

A1.

The number of children in the school has been rounded to the nearest to give .

The answer is and .

The smallest number that rounds to is .

The largest number that rounds to is .

So, the smallest possible number of children in the school is , and the largest possible number of children is .

Note: is exactly halfway between and , but rounds up to give , so we use .

A2.

The answer is and .

The smallest number that rounds to is .

The largest number that rounds to is .

Remember that is halfway between and , but rounds up to , so we must go for the smallest possible unit less than (in this case a penny less), which is .