Estimation, Checking and Explaining Answers

Estimation, Checking and Explaining Answers

Multiple Choice

Why is estimation important in everyday life?

• It helps in making quick decisions when exact values are not needed.

• It always gives the exact answer.

• It is only used in scientific research.

• It makes calculations more complicated.

Open Ended

Describe a situation where you might use estimation instead of calculating an exact value.

What is the benefit of estimating?

Multiple Choice

Which of the following words is a synonym for the word 'estimate'

• determine
• approximate

• calculate

Multiple Choice

What number could be used as an estimate for £12.95?

• £13

• £10

• £12

• £15

Multiple Choice

Estimate the sum of 489 and 267 by rounding to the nearest hundred before adding.

• 700

• 750

• 800

• 850

Multiple Choice

Estimate the sum of 78 and 66 by rounding to the nearest ten before adding.

• 130

• 140

• 150

• 160

Multiple Choice

Estimate the difference between 2,456 and 1,123 by rounding to the nearest thousand before subtracting.

• 1,000

• 1,500

• 2,000

• 2,500

Multiple Choice

A loaf of bread costs £1.89. Estimate the cost of 5 loaves.

• £8

• £10

• £5

• £12

Multiple Choice

A car uses 42 litres of petrol a week. Estimate how much it uses in a year (52 weeks).

• 1,000 litres

• 2,000 litres

• 3,000 litres

• 4,000 litres

Multiple Choice

A steel beam is 12.37 metres long. Round this length to the nearest whole metre.

• 12 metres

• 13 metres

• 14 metres

• 11 metres

Math Response

Round the following number to the nearest whole number.

23.9843

Type answer here

Correct Answer: 24

Deg^°

Rad

Open Ended

When you see the words "estimate" or "approximate" in a word problem, what do you have to do?

Open Ended

Why is it useful to round values when estimating the total cost of a project?

Multiple Choice

Mr Singh runs a triathlon made up of three sections.

He completes the first section in 48 minutes, the second section in 82 minutes and the third section in 59 minutes.

Estimate how long it takes Mr Singh to complete the triathlon, in minutes.

• 175 minutes
• 210 minutes
• 190 minutes

• 189 minutes

Multiple Choice

Charlie and his 4 friends buy tickets to a film for £6.98 each.

Estimate how much they paid altogether.

• £40
• £30
• £35
• £25

Multiple Choice

Which of the following is NOT a benefit of checking your answers?

• Avoiding simple mistakes

• Proving accuracy in multi-step questions

• Gaining extra marks in exams

• Reducing the number of questions in an exam

Multiple Select

Which of the following pairs of operations can be used as reverse operations to check answers?

• Addition and subtraction

• Multiplication and division

• Addition and multiplication

Open Ended

Explain how the reverse operation method helps you check if your answer is correct.

Multiple Choice

What is the reverse operation of division?

• subtraction

• addition

• multiplication

• equivalent

Multiple Choice

If 7 X 4 = 28, then 28 ÷ 4 =

• 4

• 7

• 11

• 28

Multiple Choice

Fill in the blank:

Addition and subtraction are inverse operations because one ____________ the other.

• Undoes

• Looks like

• Is easier than

• Is harder than

Multiple Choice

What is the main purpose of the 'Estimate and Approximate' method when checking answers?

• To get an exact answer

• To check if the answer is reasonable

• To make calculations more difficult

• To avoid using a calculator

Match

Match the number to the number it would round to the nearest 10.

• 347

• 344

• 689

• 681

• 995

350

340

690

680

1000

• 350

• 340

• 690

• 680

• 1000

Drag and Drop

A florist makes 24 centerpieces. He puts 18 roses in each centerpiece.



Which is the best way to use rounding to estimate the number of roses the florist needs? ​

Placeholder

What is the exact number of roses?​ ​

Placeholder

Drag these tiles and drop them in the correct blank above

10 x 25 = 250

360

25 x 30 = 750

30 x 30 = 900

784

672

432

20 x 25 = 500

Open Ended

A builder quotes £400 for labour and £30 for materials. The final bill is £4,030.

Does that seem reasonable? Why or why not?

Open Ended

What mistake do you think the builder made in calculating the final bill?

Open Ended

Question: A television is on sale for 25% off. The sale price is £450. What was the original price of the TV?

Calculated Answer: If you calculate $£450 / 0.25, you get £1,800.

Does the answer make sense? (Yes/No and Why)

Open Ended

Question: A car drives 200 miles at an average speed of 50 mph. How long did the trip take in minutes?

Calculated Answer: If you divide 200 miles by 50 mph, you get 4. The trip took 4 minutes.

Does the answer make sense? (Yes/No and Why)

Open Ended

Question: Sarah buys a sandwich for £3.50 and a drink for £1.50. She pays with a £10 note. How much change should she receive?

Calculated Answer: The total cost is £5.00. The change is £10.00 - £5.00 = £5.00.

Does the answer make sense? (Yes/No and Why)

Multiple Select

Which of the following is the most appropriate unit for measuring the length of a car journey?

• 50 centimetres

• 5 km

• 0.005 km

• 50 km

Multiple Select

Which of the following are the most appropriate units for measuring the volume of a typical bottle of water?

• Millilitres (mL)

• Litres (L)

• Centimetres (cm)

• Grams

Categorize

Options (8)

Yes, A is correct as their total is £12 less than B.

No, they are wrong.

No, the manager is wrong; the total is £89 not £75.

No, A only saves £4, not £10 as claimed.

Manager correct: A’s average is 12, matching the calculated mean.

No, they are wrong

A seems better because the difference looks smaller.

Choose B as their total seems smaller,

Sort the explanations into whether you think they are weak or strong.

Strong Explanation

Weak Explanation

Open Ended

A coat was £60 and is now £45. The sign says “25 % off.”

Working:
Step 1: Amount reduced = £60 – £45 = £15
Step 2: Calculate percentage reduction = (15 ÷ 60) × 100 = 25 %

✅ The sign is correct.

Write a clear explanation of why the sign is correct.

Open Ended

A bank offers a savings account with a 5% simple interest rate per year. A customer deposits £200.

The manager claims the customer will earn £100 in interest after 10 years.

Working:

Interest: £200 x 0.05 x 10 years = £100. Total amount: £200 + £105 = £305.

Is the manager correct?

Explain why the manager's claim is incorrect.

Open Ended

How does estimation help in making calculations more manageable?

Poll

How do you feel about the topics covered this lesson?

• I need more support to understand this

• I am confident I am ready to complete the work independently

• I am not sure, please come and speak to me.

• I'm not sure but I will have a go at the work, and ask you if I need help.

• I did not understand any of this