This deep dive covers Bounds in Calculations (Key for Exam!) within Bounds & Error Intervals for GCSE Mathematics. Revise Bounds & Error Intervals in Number for GCSE Mathematics with 14 exam-style questions and 5 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 5 of 7 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Bounds in Calculations (Key for Exam!)
| To find... | Use... |
|---|---|
| Maximum of A + B | UB(A) + UB(B) |
| Minimum of A + B | LB(A) + LB(B) |
| Maximum of A − B | UB(A) − LB(B) |
| Minimum of A − B | LB(A) − UB(B) |
| Maximum of A × B | UB(A) × UB(B) |
| Minimum of A × B | LB(A) × LB(B) |
| Maximum of A ÷ B | UB(A) ÷ LB(B) |
| Minimum of A ÷ B | LB(A) ÷ UB(B) |
Memory trick: For division, it's the OPPOSITE - to make a fraction big, make the top big and bottom small!
Practice questions for Bounds & Error Intervals
A length is 240 cm to the nearest 10 cm. What is the lower bound of the length?
A mass m is 45 kg to the nearest kilogram. Write down the error interval for m using inequality notation.