Upper & Lower Bounds: 3 Exam Traps in 8 Minutes | IGCSE Maths 0580 Extended

A mass is 14.2 g, correct to 1 decimal place. What's the lower bound? Students wrote 13.7, and it's wrong. In this lesson you'll master estimation and limits of accuracy (upper and lower bounds) using only real Cambridge IGCSE past-paper questions and the mistakes examiners reported. By the numbers: a bounds question appeared in 10 of the last 11 Paper 4s (March 2025 – June 2026). What's inside: ✔ Estimation: round to 1 significant figure, then calculate ✔ The sphere radius trap (π = 3, no calculator) ✔ What a bound really is: ± half of the rounding unit ✔ Combining bounds: big top, small bottom ✔ Exam level: upper bound of a density, with the mark scheme's M1/A1 marks ✔ Calculator Corner: Casio fx-991ES PLUS, type it in one go (Paper 4) ✔ Examiner's warning: 4 mistakes that cost real students marks ✔ Try-it-yourself question, answered at the end Chapters 0:00 14.2 g: lower bound? 0:42 Welcome: 10 of 11 papers 1:00 Estimation 1:37 Sphere radius (π = 3) 2:19 What is a bound? 3:05 Combining bounds 4:30 Exam level: upper bound of density 5:27 Calculator Corner: Casio fx-991ES PLUS 5:52 Examiner's warning: 4 real mistakes 6:23 Try it yourself 6:40 Summary 7:00 Answer & next lesson Past-paper questions used: 0580/43 May/Jun 2025 Q22 · 0580/41 May/Jun 2026 Q27 · 0580/22 May/Jun 2026 Q16 · 0580/22 Oct/Nov 2025 Q10(a) · 0580/21 Oct/Nov 2025 Q9 · 0580/43 May/Jun 2026 Q16. Cambridge IGCSE Mathematics 0580, Extended, syllabus 2025–2027 (E1.9, E1.10). Mathematics Multiverse is an independent channel and is not affiliated with or endorsed by Cambridge University Press & Assessment. Past-paper questions are © Cambridge University Press & Assessment and are shown for educational purposes. #IGCSE #IGCSEMaths #0580 #Bounds #Estimation #Cambridge