❌ Mistake 1: Working purely left to right
2 + 3 × 4 = 5 × 4 = 20 WRONG!
✅ Multiplication first: 2 + (3 × 4) = 2 + 12 = 14
❌ Mistake 2: Treating division and multiplication as separate priorities
12 ÷ 3 × 2 = 12 ÷ 6 = 2 WRONG!
✅ Left to right: (12 ÷ 3) × 2 = 4 × 2 = 8
❌ Mistake 3: Ignoring brackets with indices
2 × (3 + 1)² = 2 × 3 + 1² = 7 WRONG!
✅ Brackets first: 2 × (4)² = 2 × 16 = 32
This deep dive covers Common BIDMAS Mistakes within BIDMAS for GCSE Mathematics. Revise BIDMAS in Number for GCSE Mathematics with 14 exam-style questions and 22 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 3 of 9 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for BIDMAS
What does the letter 'I' stand for in BIDMAS?
Explain what BIDMAS tells us about calculations and why it is needed.
Quick recall flashcards
Calculate: 10 - 2²
**Step 1:** Indices first (BIDMAS)
2² = 4
**Step 2:** Then subtraction
10 - 4 = **6**
*(Not 10 - 2 = 8, then 8² = 64)*
Calculate: 2 + 3 × 4
**Step 1:** Multiplication first (BIDMAS)
3 × 4 = 12
**Step 2:** Then addition
2 + 12 = **14**
*(Not 2 + 3 = 5, then 5 × 4 = 20)*