EDEXCEL GCSE MATHS · FOUNDATION & HIGHER
Exam Practice: Standard Form
Powers of 10 and standard form · Number · Lesson 6 of 7 · 11 marks · 25 minutes
Name Date
Answer all questions. Show your working. Questions 1 to 5 are non-calculator.
Question 1 NON-CALCULATOR [1 mark]
Write 0.000 604 in standard form.
Question 2 NON-CALCULATOR [1 mark]
Write 7.3 × 10⁵ as an ordinary number.
Question 3 NON-CALCULATOR [2 marks]
Work out (5 × 10⁻³) × (7 × 10⁸). Give your answer in standard form.
Question 4 NON-CALCULATOR [2 marks]
Work out (8.4 × 10⁷) ÷ (2.1 × 10⁻²). Give your answer in standard form.
Question 5 NON-CALCULATOR [2 marks]
Write these numbers in order of size, starting with the smallest. 4.1 × 10⁻³, 0.0039, 42 × 10⁻⁴, 0.4 × 10⁻²
Question 6 CALCULATOR [3 marks]
The mass of one atom of gold is 3.27 × 10⁻²² grams. How many atoms of gold are there in 1 kilogram of gold? Give your answer in standard form, correct to 3 significant figures.
Answers
Check your answer only once you have written one.
Question 1 [1 mark]
6.04 × 10⁻⁴
▸ 6.04 × 10⁻⁴ B1
Question 2 [1 mark]
730 000
▸ 730 000 B1
Question 3 [2 marks]
5 × 7 = 35 and 10⁻³ × 10⁸ = 10⁵, so 35 × 10⁵ = 3.5 × 10⁶.
▸ 35 × 10⁵ or 3 500 000 seen M1
▸ 3.5 × 10⁶ A1
Question 4 [2 marks]
8.4 ÷ 2.1 = 4 and 10⁷ ÷ 10⁻² = 10⁹, so 4 × 10⁹.
▸ 4 seen, or 10⁹ seen M1
▸ 4 × 10⁹ A1
Question 5 [2 marks]
As ordinary numbers: 0.0041, 0.0039, 0.0042, 0.004. Order: 0.0039, 0.4 × 10⁻², 4.1 × 10⁻³, 42 × 10⁻⁴.
▸ All four in the correct order B2
▸ At least three converted correctly to the same form, or one pair out of order B1
Question 6 [3 marks]
1 kg = 1000 g. 1000 ÷ (3.27 × 10⁻²²) = 3.058… × 10²⁴, so about 3.06 × 10²⁴ atoms.
▸ 1 kg = 1000 g used P1
▸ 1000 ÷ (3.27 × 10⁻²²) P1
▸ 3.06 × 10²⁴ A1