NCERT Class 5 Mathematics Maths Mela Chapter 09 Coconut Farm PDF Download

Chapter 9: Coconut Farm

Observe the following array of coconuts. Write two division facts using the given multiplication fact.

[Figure: Array of 35 coconuts arranged in 5 rows and 7 columns]

5 × 7 = 35

35 ÷ 7 = 5
35 split into 7 groups has 5 in each group.

35 ÷ 5 = 7
35 split into 5 groups has 7 in each group.

Think and answer

35 ÷ 1 = ______

Dividend (N) Divisor (D) Quotient (Q)

Notice!

Dividend (N) = Divisor (D) × Quotient (Q)

Write the appropriate multiplication fact for the array shown below. Write two division facts that follow from the multiplication fact.

[Figure: Array of coconuts with blank spaces for dimensions]

_______ × _______ = _______

_______ ÷ _______ = _______

_______ ÷ _______ = _______

Teacher's Note

Division and multiplication are inverse operations. Every multiplication fact gives you two related division facts: if \( a \times b = c \), then \( c \div a = b \) and \( c \div b = a \). Notice which number becomes the dividend (the whole) and which becomes the divisor (the number of groups or group size).

Let Us Play

Identify the numbers that can fill the circles such that the numbers in the squares are the products or the quotients of the numbers in the circles.

[Figure: Circles and squares showing multiplication and division operations with numbers 36, 2; 60; 48; 36; 24; 40; 54; 42; 56; and division symbols]

Let Us Do

1. Solve the following multiplication problems. Write two division statements in each case.

   30 × 30 = ________

   _______ ÷ _______ = _______

   _______ ÷ _______ = _______

   400 × 8 = ________

   _____________________

   _____________________

   15 × 60 = _______

   _____________________

   _____________________

   200 × 16 = _________

   _____________________

   _____________________

2. Solve the following division problems. Notice the patterns and discuss in class.

   How many 3s in 150?

   _____ × 3 = 150

   150 ÷ 3 = _____

   1000 ÷ 10 = _____

   100 ÷ 10 = _____

   2000 ÷ 2 = _____

   200 ÷ 20 = _____

   3300 ÷ 3 = _____

   80 ÷ 4 = _____

   1000 ÷ 100 = _____

   300 ÷ 100 = _____

   2000 ÷ 20 = _____

   440 ÷ 44 = _____

   3300 ÷ 300 = _____

   500 ÷ 5 = _____

   1600 ÷ 4 = _____

   500 ÷ 50 = _____

   3700 ÷ 37 = _____

   630 ÷ 63 = _____

   4000 ÷ 40 = _____

   5 × _____ = 500

   500 ÷ 5 = _____

   10 × ______ = 1000

   1000 ÷ 10 = _____

   44 × __ = 440

   440 ÷ 44 = _____

   37 × ______ = 3700

   3700 ÷ 37 = _____

   What patterns do you notice here?

   What is happening to the quotients in each case?

Patterns in Division and Place Value

Now fill the place value chart.

What patterns do you notice here?

What is happening to the quotients in each case? Discuss.

Let Us Do

1. Sabina cycles 160 km in 20 days and the same distance each day. How many kilometres does she cycle each day?
2. How many notes of Rs. 100 does Seema need to carry if she wants to buy coconuts worth Rs. 4200?
3. The owner of an electric store has decided to distribute Rs. 5500 equally amongst 5 of his employees as a Diwali gift. What amount will each employee get?

   What will happen if he distributes the same amount of money among 10 employees? Will each employee get more or less? How much money would he have to distribute if everyone must get the same amount as earlier?

4. Place the numbers 1 to 8 in the following boxes so that all the four operations, division, multiplication, addition and subtraction are correct. No number must be repeated.

   [Figure: Four hexagonal boxes arranged with division, subtraction, multiplication and addition operations]

   How did you think about solving this?

   Is there more than one answer?

5. Fill in the blanks
   1. (a) _____ ÷ 18 = 100.
   2. (b) _____ ÷ 10 = 610.
   3. (c) _____ ÷ 100 = 72.
   4. (d) _____ ÷ 100 = 10.
   5. (e) 870 ÷ _____ = 87.
   6. (f) _____ ÷ 100 = 70.
   7. (g) 200 ÷ _____ = 2.
   8. (h) 130 ÷ _____ = 13.

Note for Teachers: Encourage learners to notice relationships between simple multiplication facts and multiples of tens and hundreds in division problems like the above.

Teacher's Note

When you see a division problem like 870 ÷ _____ = 87, think about the multiplication fact: what number times 87 gives 870? You can see that the dividend is 10 times the quotient, so the divisor must be 10. This pattern works whenever the dividend and quotient are related by tens and hundreds.

Mental Strategies for Division

Observe the division carefully.

1. 1248 ÷ 6

1248 = 1200 + 48
I know 1200 ÷ 6 = 200
and 48 ÷ 6 = 8
So, 1248 ÷ 6 = 200 + 8 = 208.

I can split the number into convenient parts.

2. 1992 ÷ 4

1992 = 2000 - 8
2000 ÷ 4 = 500
8 ÷ 4 = 2
So, 1992 ÷ 4 = 500 - 2 = 498.

I can do it in a different way.

3. 128 ÷ 4

To divide by 4, I can halve twice.
Half of 128 is 64.
Half of 64 is 32.

Try It!

1. 64 ÷ 4

   [Figure: Diagram showing splitting into two boxes with ÷ 4 arrows and addition]

2. 265 ÷ 5

   [Figure: Diagram showing splitting into two boxes with ÷ 5 arrows and addition]

3. 1560 ÷ 8

   [Figure: Diagram showing splitting into two boxes with ÷ 8 arrows and subtraction]

4. 4824 ÷ 24

   [Figure: Diagram showing splitting into two boxes with ÷ 24 arrows and addition]

5. 168 ÷ 8 - Halve 168 → _____ - Halve _____ → _____ - Halve _____ → _____
6. 144 ÷ 4 - Halve 144 → _____ - Halve _____ → _____

Can you give 5 such examples where you can split the number conveniently?

For which other divisors and dividend might this strategy of repeated halving work?

Key Points

• Division and multiplication are opposite operations. If \( a \times b = c \), then \( c \div a = b \) and \( c \div b = a \). Each multiplication fact gives you two related division facts.
• To divide multiples of 10 and 100, look for patterns with place value. For example, \( 4000 \div 10 = 400 \) and \( 4000 \div 100 = 40 \) - you remove zeros or think about how many times the divisor fits into the dividend.
• You can divide mentally by splitting a number into convenient parts. For example, \( 1248 \div 6 = (1200 + 48) \div 6 = 200 + 8 = 208 \), or by using subtraction: \( 1992 \div 4 = (2000 - 8) \div 4 = 500 - 2 = 498 \).
• Dividing by 4 can be done by halving twice. Dividing by 8 can be done by halving three times. This works because \( 4 = 2 \times 2 \) and \( 8 = 2 \times 2 \times 2 \).
• The relationship Dividend = Divisor × Quotient helps you check your division or find a missing number when two are known.

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