1 EstimationStrategies Press Ctrl-A ©2009 – Not to be sold/Free to use Stage 5 Year 9

2 End of Slide Level of accuracy - approximation When find the area of a circle the 8 decimal places on the calculator may not be relevant. r = 2.9cm A =  r 2 A =  x A Upper =  x A Lower =  x = = = More than 2 significant figures - meaningless. = 26 Use the significant figures in question.

3 End of Slide Level of accuracy - approximation Find the area of the square m Three significant figures Area = s 2 = = = 7.56 cm 2

4 End of Slide Level of accuracy - approximation Find the area of the square m Four significant figures Volume = s 3 = = = 4956 cm 3