# Rounding: closest to

Purpose

This exercise is for students to use independently of the teacher to practice number properties.

Achievement Objectives
NA2-4: Know how many ones, tens, and hundreds are in whole numbers to at least 1000.
NA2-1: Use simple additive strategies with whole numbers and fractions.
Specific Learning Outcomes

round to the nearest ten or hundred

use the sign that means “approximately equals”

Description of Mathematics

Grouping/place value, EA (Stage 5)

Required Resource Materials
Practice exercises with answers (PDF or Word)
Activity

### Prior knowledge.

Identify when a number is “closer to”

### Background

This activity is an introductory exercise designed to introduce students to the idea of approximate numbers and rounding. It is knowledge based.  This exercise is about rounding numbers to the nearest 10 or 100and introduces students to talking about the approximate size of numbers. In doing this it also introduces them to a new symbol (≈ or the ‘squiggly equals’). Teachers need to be aware that this symbol needs to be used in the context of a problem, with the questions in this exercise being a very simple class of these.

Rounding numbers can only be sensibly done in a context.  672 can be correctly rounded to 670 adn also to 700, the context of the problem determines whichis more sensible. If taken out of the context of the problem, and the numbers in that problem, its use can lead to some nonsensical statements. For example, saying that 150 is approximately 200, or pi (3.1415928…) is close to zero is not very helpful mathematically. However in the context of the problem 47 ÷ 123,456,789 saying that 47 ≈ 0, so the answer is approximately zero does make sense