Approximation and Estimation practice questions

Secondary 1 topics, the foundation the O-Level Mathematics 4052 syllabus builds on. Every question below has a full worked solution.

When a student gets a question wrong in Math Amigo, it does not show the answer straight away. It reads the working, identifies the step that went wrong, and asks a question that points at the correction. The worked solution is there once a genuine attempt has been made.

Practise approximation and estimation free

What this topic covers

Worked examples

Example 1

Correct 84.77084.770 to 1 decimal place.
Show the worked solution
  • Identifythedigitinthetenthsplace.Identify the digit in the tenths place.
  • Examinethenextdigit:itis7.Examine the next digit: it is 7.
  • Since 7 $\geq$ 5, we round up.
  • $84.770 = 84.8$ (to 1 decimal place)

Answer: 84.884.8

Example 2

State the number of significant figures in 0.00041200.0004120.
Show the worked solution
  • Leadingzerosarenotsignificant(Rule3).Atrailingzeroafterthedecimalpointissignificant(Rule4).Digits:4,1,2,0.Leading zeros are not significant (Rule 3). A trailing zero after the decimal point is significant (Rule 4). Digits: 4, 1, 2, 0.
  • $0.0004120$ has $4$ significant figures.

Answer: 44

Example 3

Round off 0.0004529400.000452940 to 4 significant figures.
Show the worked solution
  • Leading zeros are not significant. The first 4 significant figures are 4, 5, 2, 9. The next digit is 4 ($< 5$), so round down: $0.000452940 \approx 0.0004529$ (to 4 s.f.).

Answer: 0.00045290.0004529

Questions parents ask

Is it really free?

The free plan is permanent and does not ask for a card. It has daily limits on the AI feedback, and the paid plans lift them.

Which syllabus does this follow?

O-Level Mathematics (4052), for Singapore secondary students. Math Amigo covers Secondary 1 to 4, both O-Level Mathematics and Additional Mathematics.

Will it just show my child the answer?

No. On a wrong answer it looks at the working, points to the step that went wrong, and asks a question that helps the student find the correction. The full worked solution is available after a genuine attempt.

Other Secondary 1 topics