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MasterMaths online tuition: Year 7 Maths BIDMAS With Worked Examples

Year 7 Maths BIDMAS With Worked Examples

Writer: Ryan Harvey
Ryan Harvey
Oct 12
3 min read

BIDMAS helps pupils calculate expressions containing several different operations. It stands for brackets, indices, division and multiplication, addition and subtraction. The critical distinction is that multiplication and division have equal priority, as do addition and subtraction. Within each pair, calculations are completed from left to right. Understanding that prevents many common Year 7 errors.


What the letters actually mean

Evaluate brackets first and then indices. Next handle multiplication and division from left to right, and finally addition and subtraction from left to right. The acronym does not mean that division must always be done before multiplication. For instance, 12 ÷ 3 × 2 = 4 × 2 = 8. Multiplying 3 × 2 first changes the grouping and would give the wrong value.


A first example with multiplication

Evaluate 7 + 3 × 4. Calculate 3 × 4 = 12, then add 7 to get 19. Compare this with (7 + 3) × 4 = 10 × 4 = 40. The digits and operators are the same, but the brackets change the intended calculation. Invite students to describe the difference before memorising the procedure. One worked example with a reason can teach more than many mechanical repetitions.


Indices before multiplication

Consider 2 + 3² × 4. The square is 3² = 9, then 9 × 4 = 36, and finally 2 + 36 = 38. An index belongs to its base: 3² means three multiplied by three. The expression (2 + 3)², however, gives 25 because the brackets are squared together. Underline the base when a question contains several nearby numbers.


Equal priority operations go left to right

Calculate 24 ÷ 4 × 3. Starting at the left gives 6 × 3 = 18. Likewise, for 10 − 6 + 2, first compute 10 − 6 = 4 and then add 2, giving 6. You do not perform the addition first merely because A appears before S in the acronym. Encourage one change at a time on a fresh line so the sequence stays visible.


Include negative numbers carefully

For 5 − (−3) × 2, first multiply −3 × 2 = −6. Then 5 − (−6) = 11. Brackets around a negative number are not always instructions to add or multiply everything inside; sometimes they simply make the sign visible. If negative arithmetic is uncertain, practise subtracting negative values separately before combining them with the full order of operations.


A reliable method for mixed questions

Copy the original expression, circle brackets, mark powers, and complete one priority level at a time. For 6 + 2 × (5 − 1)², first (5 − 1) = 4, then 4² = 16, then 2 × 16 = 32, and finally 6 + 32 = 38. Check the answer on a calculator only after attempting it independently, and explain why each operation came next.


Frequently asked questions

Is BODMAS different from BIDMAS?

No. Both express the same operation priorities using slightly different terminology.

Must multiplication always precede division?

No. At equal priority, work from left to right.

Explore further KS3 resources

The related resources below address supporting skills. Choose those that match the specific questions you find difficult rather than reading every article in one sitting.

Book a free maths introduction

If a topic remains difficult after independent practice and school feedback, discuss whether one-to-one online lessons would be appropriate. MasterMaths offers a free 20-minute introduction with Ryan to clarify needs and practical arrangements. Learning progress varies, and no specific grade increase is guaranteed.

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