Yusuf uses his calculator memory. He calculates 12.5 × 8 and stores the answer in memory. He then recalls the memory and adds 47. Work out the final result.
(Total for Question 7 is 2 marks)
8
Work out (3/4) ÷ (1/8).
(Total for Question 8 is 2 marks)
9
Work out (15 - 3) ÷ (2 + 1).
(Total for Question 9 is 2 marks)
10
Work out √81 + 23.
(Total for Question 10 is 2 marks)
11
A calculator shows 3.333 as the result of 10 ÷ 3, rounded to 3 decimal places. Give a lower bound and an upper bound for the exact value of 10 ÷ 3.
(Total for Question 11 is 2 marks)
12
Callum uses M+ to store three numbers: he enters 4.2, presses M+; 5.6, presses M+; 3.8, presses M+. He then recalls the memory and divides by 3 to find the average. Work out the average to 3 decimal places.
(Total for Question 12 is 2 marks)
13
A calculator displays 2.35 to 3 significant figures for the value of 7 ÷ x. Find the lower and upper bounds for x, giving your answers to 3 decimal places.
(Total for Question 13 is 3 marks)
14
Erin uses M+ to enter 120, 85 and 95 into the calculator memory. She recalls the memory and divides by 3 to find the mean. Work out the mean.
(Total for Question 14 is 3 marks)
15
Work out 2 1/2 × 3 1/4 and give your answer as a mixed number. You may use the fraction key on a calculator.
(Total for Question 15 is 3 marks)
16
Show that (√50 - √2)(√50 + √2) = 48. Hence find the exact value of √50 - √2.
(Total for Question 16 is 4 marks)
Mark scheme · 2.2D Using a Calculator: Fluency and Exam Drill
Question 1
B1 45 cao
Answer: 45
Question 2
B1 30 cao
Answer: 30
Question 3
B1 69 cao
Answer: 69
Question 4
B1 48 cao
Answer: 48
Question 5
B1 5/6 cao
Answer: 5/6
Question 6
B1 4 cao
Answer: 4
Question 7
M1 use memory or calculate 12.5 × 8 = 100 (method shown) oe
A1 147 cao
Answer: 147
Question 8
M1 correct method, e.g. (3/4) × 8 or (3/4) ÷ (1/8) oe
A1 6 cao
Answer: 6
Question 9
M1 identify (15-3)=12 and (2+1)=3 or equivalent method
A1 4 cao
Answer: 4
Question 10
M1 correct method e.g. √81=9 and 23=8 shown
A1 17 cao
Answer: 17
Question 11
M1 state bounds for the displayed value 3.333 to 3 d.p.: 3.3325 ≤ value < 3.3335
A1 lower bound 3.3325 and upper bound 3.3335 cao
Answer: 3.3325 ≤ 10/3 < 3.3335
Question 12
M1 sum the numbers or show memory total 13.6
A1 4.533 cao (13.6/3 = 4.533333... rounded to 3 d.p.)
Answer: 4.533
Question 13
M1 state bounds for 2.35 to 3 s.f.: 2.345 ≤ y < 2.355
M1 use x = 7 / y to get bounds for x (invert bounds) oe
A1 x is such that 2.972 < x ≤ 2.985 (answers to 3 d.p.)
Answer: 2.972 < x ≤ 2.985
Question 14
M1 sum the three numbers to get 300 or show use of memory total
M1 divide by 3 shown
A1 100 cao
Answer: 100
Question 15
M1 convert to improper fractions or use fraction key: 5/2 × 13/4 oe
M1 multiply to get 65/8 or show calculator method
A1 8 1/8 cao
Answer: 8 1/8
Question 16
M1 use (a - b)(a + b) = a2 - b2 with a = √50, b = √2 (cso)
M1 evaluate a2 - b2 = 50 - 2 = 48 (cso)
M1 rearrange to give √50 - √2 = 48/(√50 + √2) (cso)