Real Numbers | Exercise 1.1

Question 4

Given that HCF (306, 657) = 9, find LCM (306, 657).

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Solution

The product of two numbers is equal to the product of their HCF and LCM.

Step 1 — Identify Given Values

We are given two numbers. Let's call them a and b. So, a = 306. And b = 657. We are also given their HCF. HCF (306, 657) = 9.

Step 2 — Calculate LCM

Let's use the relationship between HCF, LCM, and the numbers. We know the formula: LCM×HCF=Product of the two numbers\text{LCM} \times \text{HCF} = \text{Product of the two numbers} We can rearrange this formula to find the LCM. LCM=Product of the two numbersHCF\text{LCM} = \frac{\text{Product of the two numbers}}{\text{HCF}} Now, let's substitute the given values into the formula. LCM=306×6579\text{LCM} = \frac{306 \times 657}{9} Let's perform the multiplication in the numerator first. LCM=2010429\text{LCM} = \frac{201042}{9} Now, we perform the division. LCM=22338\text{LCM} = 22338

LCM(306,657)=22338\boxed{\text{LCM} (306, 657) = 22338}

Answer

(i) The LCM (306, 657) is 22338.

More questions in Exercise 1.1

Q1

Express each number as a product of its prime factors:

(i) 140 (ii) 156 (iii) 3825 (iv) 5005 (v) 7429

Q2

Find the LCM and HCF of the following pairs of integers and verify that LCM × HCF = product of the two numbers.

(i) 26 and 91 (ii) 510 and 92 (iii) 336 and 54

Q3

Find the LCM and HCF of the following integers by applying the prime factorisation method.

(i) 12, 15 and 21 (ii) 17, 23 and 29 (iii) 8, 9 and 25

Q4

Given that HCF (306, 657) = 9, find LCM (306, 657).

Q5

Check whether 6n6^n can end with the digit 0 for any natural number nn.

Q6

Explain why 7×11×13+137 \times 11 \times 13 + 13 and 7×6×5×4×3×2×1+57 \times 6 \times 5 \times 4 \times 3 \times 2 \times 1 + 5 are composite numbers.

Q7

There is a circular path around a sports field. Sonia takes 18 minutes to drive one round of the field, while Ravi takes 12 minutes for the same. Suppose they both start at the same point and at the same time, and go in the same direction. After how many minutes will they meet again at the starting point?

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