Question

A.Find the L.C.M of 18, 40, and 75.
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Answer 1

1800

Explanation:

Hello,

First of all we need to find the prime factorisation of the numbers.

18 = 2 * 3 * 3

40 = 2 * 2 * 2 * 5

75 = 3 * 5 * 5

It means that the LCM should have 5 * 5 , 2 * 2 * 2 and 3 * 3

Then LCM = 3 * 3 * 2 * 2 * 2 * 5 * 5 = 1800

Hope this helps.

Do not hesitate if you need further explanation.

Thank you

Answer 2

1800

Explanation:

→ First of all we need to find the prime factorisation of the numbers.

18 = 2 × 3 × 3 or 2 × 3²

40 = 2 × 2 × 2 × 5 or 2³ × 5

75 = 3 × 5 × 5 or 5² × 3

→ Now find the number that appear twice or more and write them down

3 and 3 from 18

2, 2 and 2 from 40

5 and 5 from 75

→ Now multiply all of these numbers together

3 × 3 × 2 × 2 × 2 × 5 × 5 = 3² × 2³ × 5² = 1800