You will discover the notion of the divisor of the natural number.
Learning effect
You recognize and write down the divisors of the natural numbers.
You identify the greatest common divisor of two natural numbers.
You use English to describe the method of identifying the greatest common divisor of two natural numbers.
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Prepare 10 cards with oneoneone of the following numbers: 2, 3, 4, 6, 8, 12, 15, 24, 30 or 48. Revise the information about the division with the remainderthe remainderthe remainder.
Today you are going to discover the notion of the divisor of the natural numbernatural numbernatural number. You are also going to determine the greater common divisor of two natural numbers.
Task 1
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Analyse the slideshow concerning the divisors of the number 6.
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Consider:
What number is the leastthe leastthe least divisor of number six?
Is the number 1 divisor of each natural numbernatural numbernatural number?
What number is the greatestthe greatestthe greatest divisor of the number 6?
Is each natural numbernatural numbernatural number a divisor of itself?
Number 1 is the leastthe leastthe least divisor of number 6 and each natural numbernatural numbernatural number.
The greatestthe greatestThe greatest divisor of number 6 is 6.
Every natural non‑zero number is its greatest divisor.
All positive natural numbers are the divisors of zerozerozero.
Task 2
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Write all the divisors of the following numbers:
a) 4 b) 18 c) 25 d) 36
Task 3
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Write down all the even divisors of number 40.
Task 4
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Write all the divisors of number 27 and of number 45. Next, compare the numbers you have written down and they identify the common divisors of the numbers 27 and 45. Choose the greatest one.
Task 5
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Analyse the illustration and note how the greatest common divisorthe greatest common divisorthe greatest common divisor is written. The writing described symbolically as GCD (16, 20) = 4 means that the greatest common divisorthe greatest common divisorthe greatest common divisor of the numbers 16 and 20 is number 4.
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Task 6
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Draw two of the cards you have prepared for the lesson. Indicate and write the greatest common divisorthe greatest common divisorthe greatest common divisor of the drawn numbers. Repeat the activity three times.
Task 7
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Artur has bought 42 sweets and 28 tangerines for his birthday party. How many children can he invite if each child is to get the same number of the tangerines and the sweets?
Task 8
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An extra task: Use the Internet to look for the information about perfect numbers. Give three examples of them.
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Remember:
Number 1 is the leastthe leastthe least divisor of every natural numbernatural numbernatural number.
Every natural non‑zero number is its greatest divisor.
All positive natural numbers are the divisors of zerozerozero.
Do the summarising tasks.
Exercises
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Exercise 1
Exercise 2
Edyta’s mum has got 18 red and 12 white roses. How much more bouquets can she make to put the same number of red and white roses in each bouquet? How many red and how many white roses are there in each of the bouquets?
GCD (18, 12) = 6 Edyta’s mum can make 6 such bouquets. There are 3 red and 2 white roses in each bouquet.
Exercise 3
Identify:
a) GCD (10, 15)
b) GCD (5, 35)
c) GCD (16, 28)
d) GCD (21, 26)
Describe the method of identifying the greatestthe greatestthe greatest common divisor of two natural numbers in English.
Hint:
a) GCD (10, 15) = 5
b) GCD (5, 35) = 5
c) GCD (16, 24) = 8
d) GCD (21, 26) = 1
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Exercise 4
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Glossary
divisor of the number
divisor of the number
dzielnik liczby - liczba przez którą dana liczba naturalna dzieli się bez reszty
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the greatest common divisor
the greatest common divisor
największy wspólny dzielnik dwóch liczb - największa liczba, która dzieli bez reszty obie liczby