Questions on standard form 3

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What is 9 x 10⁴ x 0.013? (hint: convert the second number to standard form first)

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What is (6 x 10⁸) ÷ (5 x 10⁴)?

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What is 1.4 x 10⁸ ÷ 700? (hint: convert the second number to standard form first)

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What is 4.5 x 10⁶ ÷ (9 x 10^-5)?

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What is 0.7 x 0.2? By changing each number into standard form, can you deduce the rule for counting the number of decimal places in such a multiplication?

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(You may use a calculator) A light year is defined as the distance light travels in a year. The speed of light is 3 x 10⁸ metres per second and a year has approximately 3.1 x 10⁷ seconds.

a) How long is a light year in metres?
b) The nearest star (apart from the Sun) is Proxima Centauri which is 4.3 light years away. How far is this in metres?
c) The Sun is 150 million km away. How many times further away is Proxima Centauri than the Sun? (Hint: convert the Sun's distance to standard form, and remember to convert it to metres)