2021/22 S3 Ex.1D Significant Figures

2021/22 S3 Ex.1D Significant Figures

by LHK

How to round

• Significant figures are counted from left to right starting at the first non-zero digit.

Example 1

Round 8 638 902  to 3 significant figures.

​Law of Indices from S1

​Do you still remember what are indies? 次方?

​

​Do you still remember how indices work?

​

​Before we start Indices in S3, let's have a revision session!

Round 8 638 902  to 3 significant figures.

• First three significant figures starting from left are 8, 6 and 3

• Fourth digit is 8, which is 5 or more - Round up! 進位!

• so it is 8 640 000

Multiple Choice

Round 57263 to 3 significant figures.

• 57263

• 57270

• 57300

• 57260

Example 2

Round 400 023  to 3 significant figures

Round 400 023  to 3 significant figures.

• First three significant figures starting from left are 4, 0 and 0

• Fourth digit is 2, which is less than 5 - NO round up

• so it is 400 000

Multiple Choice

Round 38041 to 3 significant figures.

• 38000

• 38040

• 38100

• 38041

Example 3

Round 0.0056 189 to 3 significant figures

Round 0.0056189  to 3 significant figures.

• First three significant figures starting from left are 5, 6 and 1

• Fourth digit is 9, which is 5 or more - round up the third significant figure

• so it is 0.00562

• Do not replace digits 8 and 9 with 0's as it will have 5 significant figures then.

State the number of significant figures

• 38041

• 0.00521

• 451000

• 256010

The number of significant figures in

• 38041 are 5

• 0.00521 are 3

• 451000 are 3, 4, 5 or 6

• 256010 are 5 or 6.

Multiple Select

State the number of significant figures in 242300

• 4

• 5

• 6

Multiple Choice

State the number of significant figures in 0.006859

• 7

• 6

• 5

• 4

Multiple Choice

State the number of significant figures in 0.172046

• 3

• 4

• 5

• 6