Approximating Calculations Demonstration This resource provides animated demonstrations

Copy & Complete this table Original Number 52 232 1317 35 9 4. 7

Copy & Complete this table Original Number Rounded to 1 Significant Figure 52 50

How much taller is the giraffe than the dog? ? 96. 3 cm 5.

How much taller is the giraffe than the dog? Whose method do you prefer?

Jay wants to buy 17 doughnuts for his friends. 1 doughnut costs 45 p

Instead of finding the exact result of a calculation, sometimes it is better to

To approximate the value of a calculation, we round each number to 1 significant

Approximate the answer to each question. (round each number to 1 significant figure) 1)

Approximating Calculations DEMO Rewrite the calculation with each number rounded to 1 significant figure.

Approximating Calculations DEMO YOUR TURN Rewrite the calculation with each number rounded to 1

Questions? Comments? Suggestions? …or have you found a mistake!? Any feedback would be appreciated

Slides: 30

Download presentation

Approximating Calculations – Demonstration This resource provides animated demonstrations of the mathematical method. Check animations and delete slides not needed for your class.

Copy & Complete this table Original Number 52 232 1317 35 9 4. 7 10. 5 252. 7 0. 62 0. 9517 Number Rounded to 1 Significant Figure

Copy & Complete this table Original Number Rounded to 1 Significant Figure 52 50 232 200 1317 1000 35 40 9 10 4. 7 5 10 252. 7 300 0. 62 0. 6 0. 9517 1

How much taller is the giraffe than the dog? ? 96. 3 cm 5. 27 m

How much taller is the giraffe than the dog? Whose method do you prefer? 527 – 96. 3 = 430. 7 cm 527 – 96 = 431 cm ? 5 m – 1 m = 4 m 96. 3 cm 5. 27 m

Jay wants to buy 17 doughnuts for his friends. 1 doughnut costs 45 p John has £ 12 Does he have enough money to buy the doughnuts? We can approximate the total. 17 20 45 p 50 p 20 × 50 = 1000 £ 10

Instead of finding the exact result of a calculation, sometimes it is better to approximate the solution. Jane calculates how much she spent on lunch this week. A farmer calculates the amount of seed they need for their field. Which of these calculations are ok to approximate? On a school trip, Mr Jones calculates the number of students on the bus back. A doctor calculates the quantity of drugs he gives his patient. Mrs Smith calculates the tax she will pay this year. Jenny calculates how far she ran this morning.

To approximate the value of a calculation, we round each number to 1 significant figure. On Monday John spent £ 3. 24 on lunch. … Tuesday … £ 4. 01 … … Wednesday … £ 2. 32 … … Thursday … £ 5. 07 … … Friday … £ 2. 14 … 3 4 2 5 2 How much did he spend that week? New Oak school has 462 students. Stanmoore … 546. . . Woodbridge … 219. . . How many students are there in total? 3 + 4 + 2 + 5 + 2 Spending ≈ £ 16 Approximately equal to. 500 200 500 + 200 Students ≈ 1200

Approximate the answer to each question. (round each number to 1 significant figure) 1) Anne spent £ 5. 82 on lunch and £ 6. 12 on dinner. Approximately how much did she spend in total? 2) Marcus had £ 17. 82. He spent £ 2. 82 on snacks and £ 4. 32 on a bus ticket. Approximately how much does he have left? 3) John wants to buy 13 sweets. Each sweet costs 32 p. Approximately how much will he spend? 4) 1 litre of paint covers 7. 65 m 2. How many litres of paint does Mike need to cover 44. 8 m 2 of wall? 5) Ami earns £ 12. 45 an hour. After 52 ½ hours how much will she earn? 6) There are 2712 students in the district. 540 of them take a bus to school. 255 of them ride in a car. How many don’t take a bus or car?

Approximate the answer to each question. (round each number to 1 significant figure) 1) Anne spent £ 5. 82 on lunch and £ 6. 12 on dinner. Approximately how much did she spend in total? ≈ £ 12 2) Marcus had £ 17. 82. He spent £ 2. 82 on snacks and £ 4. 32 on a bus ticket. Approximately how much does he have left? ≈ £ 11 ≈ £ 3 3) John wants to buy 13 sweets. Each sweet costs 32 p. Approximately how much will he spend? 4) 1 litre of paint covers 7. 65 m 2. How many litres of paint does Mike need to cover 44. 8 m 2 of wall? ≈ 5 L 5) Ami earns £ 12. 45 an hour. After 52 ½ hours how much will she earn? ≈ £ 500 6) There are 2712 students in the district. 540 of them take a bus to school. 255 of them ride in a car. How many don’t take a bus or car? ≈ 2200

Approximating Calculations DEMO Rewrite the calculation with each number rounded to 1 significant figure.

Approximating Calculations DEMO YOUR TURN Rewrite the calculation with each number rounded to 1 significant figure.

Approximating Calculations DEMO Rewrite the calculation with each number rounded to 1 significant figure.

Approximating Calculations DEMO YOUR TURN Rewrite the calculation with each number rounded to 1 significant figure.

Approximating Calculations DEMO Rewrite the calculation with each number rounded to 1 significant figure. YOUR TURN ① ② ③ ④ ⑤ ⑥ ⑦

Approximating Calculations DEMO Rewrite the calculation with each number rounded to 1 significant figure. YOUR TURN ① ② ③ ④ ⑤ ⑥ Answers ⑦

Questions? Comments? Suggestions? …or have you found a mistake!? Any feedback would be appreciated . Please feel free to email: tom@goteachmaths. co. uk