Order of operations and long division
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What is the Order of Operations?
- The order of operations is a set of rules that tells us which calculation to do first in a maths problem.
- It helps everyone get the same answer, so there is no confusion.
- The order is: Brackets first, then Indices (powers), then Division and Multiplication, and finally Addition and Subtraction.
- A simple way to remember it is the word BIDMAS (Brackets, Indices, Division, Multiplication, Addition, Subtraction).
- If you don't follow this order, you might get a different answer.
Why the Order Matters
- Different orders can give different answers for the same problem.
- For example, 1 + 2 × 3 = 7 because we multiply first: 2 × 3 = 6, then add 1.
- If we added first, we would get (1 + 2) × 3 = 9, which is wrong.
- The order of operations is a convention – a rule that everyone agrees to follow.
- Using the correct order keeps maths clear and consistent.
Brackets First
- Brackets are symbols like ( ) that group numbers together.
- Always work out what is inside the brackets first.
- For example, (2 + 3) × 4 = 5 × 4 = 20.
- If there are brackets inside brackets, work from the inside out.
- Example: [2 × (3 + 4)] − 5 = [2 × 7] − 5 = 14 − 5 = 9.
Indices (Powers)
- An index (plural: indices) is a small number that tells you how many times to multiply a number by itself.
- For example, 52 means 5 × 5 = 25.
- Indices come after brackets but before multiplication, division, addition, and subtraction.
- So in 3 + 52, we first do 52 = 25, then add 3 to get 28.
- In 3 × 52, we first do 52 = 25, then multiply by 3 to get 75.
Multiplication and Division
- After brackets and indices, do multiplication and division next.
- They have the same importance, so work from left to right.
- For example, 10 ÷ 2 × 3 = 5 × 3 = 15 (do division first because it is on the left).
- If you did multiplication first, you would get 10 ÷ 6 = 1.67, which is wrong.
- Remember: multiplication and division are done before addition and subtraction.
Addition and Subtraction
- Addition and subtraction are done last.
- They also have the same importance, so work from left to right.
- For example, 10 − 3 + 2 = 7 + 2 = 9 (do subtraction first because it is on the left).
- If you did addition first, you would get 10 − 5 = 5, which is wrong.
- Always check your work by following the order step by step.
Long Division
- Long division is a method for dividing big numbers step by step.
- It helps you find the answer (quotient) and the leftover part (remainder).
- For example, 847 ÷ 7: 7 goes into 8 once (1), remainder 1; bring down 4 to make 14; 7 goes into 14 twice (2), remainder 0; bring down 7; 7 goes into 7 once (1), remainder 0. So 847 ÷ 7 = 121.
- You write the steps in a special layout with the divisor on the left and the quotient on top.
- Practice with smaller numbers first, like 96 ÷ 4 = 24.
Checking Your Answers
- Always check your answers to avoid mistakes.
- Use estimation – round the numbers to get a rough answer.
- For example, 847 ÷ 7 is about 840 ÷ 7 = 120, so 121 is close.
- Use inverse operations – do the opposite operation to check.
- For division, multiply the quotient by the divisor to see if you get the original number: 121 × 7 = 847.
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1.What is the correct order of operations?
Easy- ABrackets, then indices, then multiplication and division, then addition and subtraction
- BAddition, then subtraction, then multiplication, then division
- CLeft to right, no matter what
- DIndices, then brackets, then addition and subtraction, then multiplication and division
2.In the expression 6 + 2 × 3, you should do the addition first.
EasyTrue or false?
3.What is the value of 23 + 1?
Medium- A9
- B7
- C10
- D8
4.Which of the following expressions equal 12? (select all that apply)
Medium- A2 × (3 + 3)
- B2 × 3 + 3
- C3 × (2 + 2)
- D3 + 3 × 2
5.Put the steps of the order of operations in the correct order:
Easy- Addition and subtraction
- Brackets
- Indices
- Multiplication and division
6.Match each expression with its value.
Medium- 5 + 2 × 3
- (5 + 2) × 3
- 5 × 2 + 3
- 21
- 11
- 13
7.Match each expression with its correct value.
Medium- 2 + 3 × 4
- (2 + 3) × 4
- 2 × 32
- 14
- 20
- 18
8.Put the steps of the order of operations in the correct order (first to last).
Easy- Brackets
- Indices (powers)
- Multiplication and division
- Addition and subtraction
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