S1 8.2 Numerical Estimation

Which of the following estimation strategies must NOT give an approximate value greater than the exact value?

I. Rounding off

II. Rounding up

III. Rounding down

• I only

• II only

• III only

• I and II only

If the approximate value of 759 is 760, which of the following methods may be used in the estimation?

I. Rounding off

II. Rounding up

III. Rounding down

• I only

• II only

• I and II only

• I and III only

By rounding off each number to the nearest ten, estimate the value of

812 + 659 − 107 + 521 − 226.

• 1659

• 1660

• 1650

• 1700

By rounding up each number to the nearest integer, estimate the value of

−53.4 + 20.7 + 73.6 − 55.3 + 25.8.

• 13

• 12

• 11

• 10

By rounding down each number to the nearest hundred, estimate the value of

4 376 + 1826 − 492 + 1520.

• 7300

• 7240

• 7230

• 7200

Which of the following estimations has used rounding up as the estimation strategy?

• 
• 
• 
• 

Mia wants to buy three items of prices $52.3, $65.4 and $97.8 in a shop. It is given that a customer can get a lucky draw ticket for any purchase of $200 or above in the shop. To determine whether Mia can get a lucky draw ticket or not, which of the following expressions should be used to estimate the total purchase made by her?

• $50 + $60 + $90

• $50 + $60 + $100

• $50 + $70 + $100

• $60 + $70 + $100

John wants to buy four items of prices $88, $125, $163 and $209. John has only $600. To determine whether John has enough money to buy all the items needed, which of the following expressions should be used to estimate the total purchase made by him?

• $80 + $120 + $160 + $200

• $90 + $120 + $160 + $210

• $90 + $130 + $160 + $210

• $90 + $130 + $170 + $210

Alan buys 8 bottles of milk for the unit price between $7 and $12. Which of the following CANNOT be the total price of the milk?

• $56.5

• $64.5

• $80.5

• $96.5

Coey wants to buy three items of prices $71, $52 and $79. At least how many $100 banknotes should Coey bring to buy all the items needed?

• 2

• 3

• 4

• 5