choose and use estimation and rounding to check and explain the reasonableness of calculations including the results of financial transactions

How Bloomi helps with this

This is a readiness-year topic that builds towards the next NAPLAN year. Bloomi practises it as curriculum mastery, never test drilling.

What this looks like in the classroom

• using proficiency with basic facts to estimate the result of a calculation and say what amounts the answer will be between; for example, \(5\) packets of biscuits at \(\$2.60\) each will cost between \(\$10\) and \(\$15\) as \(5 \times\) \(\$2 =\$10\) and \(5\times\$3=\$15\)
• using rounded amounts to complete an estimated budget for a shopping trip or an excursion, explaining why overestimating the amounts is appropriate
• recognising the effect of rounding in addition and multiplication calculations; rounding both numbers up, both numbers down and one number up and one number down, and explaining which is the best approximation and why