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Multiplying a fraction by the natural number

Source: licencja: CC 0.

Mnożenie ułamka przez liczbę naturalną

Learning objectives

  • You will learn how to multiply a natural number by the common fraction.

Learning effect

  • You multiply a fraction by a natural number.

  • You calculate the product of the mixed number by the natural number.

  • You do the tasks by using the multiplication of the fraction and the natural number.

  • You use English to describe the method of multiplying a fraction by the natural number.

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nagranie abstraktu

Read the story of “The Rome merchant” and do the following exercises.

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nagranie abstraktu

The Rome merchant went to faraway places to buy ambers. Before he left, he had offered some gifts to the gods to make benefits during the dangerous journey. He gave 24 denarii for this purpose and he started his journey.

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nagranie abstraktu

Imagine you are the Rome merchant. Prepare 24 denarii (e.g. balls of modelling clay), visit the temples and leave the following amount of denarii in each place:

  • The MERKURY temple – you should leave for yourself only 13 of your money.

  • The NEPTUN temple – you should leave for yourself only 12 of your money.

  • The JUPITER temple - you should leave for yourself only 14 of your money.

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nagranie abstraktu

Write the answers to the following questions on a piece of paper:

  • How many denarii did the merchant have after he had made the offerings in all the temples?

  • How many denarii did he leave in each temple?

  • What part of 24 denarii was left in each temple?

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nagranie abstraktu

Repeat the journey visiting the temples in a different order. Answer the questions again and discuss what answers depend on the order of visiting the temples.

Task 1
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nagranie abstraktu

Watch the slideshow to observe how common fractions are multiplied by natural numbers.

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Pokaz slajdów przedstawia w jaki sposób mnożymy ułamki zwykłe przez liczbę naturalną. Instrukcja obsługi z poziomu klawiatury: 1. Uruchomienie aplikacji - ENTER, 2. Na każdym ze slajdów czytany jest automatycznie tekst alternatywny po polsku, 3. Przy pierwszym uruchomieniu na pierwszym slajdzie, czytanie tekstu po angielsku - TAB, 4. Przejście między slajdami: do następnego slajdu - TAB, do poprzedniego slajdu - TAB + SHIFT, 5. Przejście do czytania napisu po angielsku - strzałka w górę + strzałka w dół (czyta tekst po angielsku widoczny na slajdzie).
Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

Conclusion:

To multiply the fraction by a natural numbernatural numbernatural number, we multiply the numerator by the natural number (the denominator remains the same).

Task 2
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nagranie abstraktu

Multiply the fractions by the natural numbers. Write the result in the simplest formsimplest formsimplest form

a) 3·27=

b) 45·3=

c) 24·16=

d) 56·12=

Task 3
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nagranie abstraktu

The bag of the KIT cat food weighs 225 kg. How many kilos do 5 of these bags weigh?

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nagranie abstraktu

Conclusion:

  • To multiply a natural numbernatural numbernatural number by the mixed numbermixed numbermixed number, we convert the mixed number into an improper fraction and then we multiply the natural number by the fraction we have got.

  • To multiply a natural number by a mixed number, we multiply the natural number by the whole part of the mixed number and the fraction, and then we add the obtained results.

Task 4

An extra task:

Using the equation 31231·248=840, calculate the productproductproduct of 31231·124.

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nagranie abstraktu

Remember:

  • To multiply the fraction by a natural numbernatural numbernatural number, we multiply the numerator by the natural number (the denominator remains the same).

  • When we multiply a natural number by a fraction, we can reduce the fraction to make the operation easier.

  • To multiply a natural number by the mixed numbermixed numbermixed number, we convert the mixed number into an improper fraction and then we multiply the natural number by the fraction we have got.

  • To multiply a natural number by a mixed number, we multiply the natural number by the whole part of the mixed number and the fraction, and then we add the obtained results.  

Check what you have learned by doing the following tasks.

Exercises

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Exercise 1
Wersja alternatywna ćwiczenia: Determine which sentences are true. Możliwe odpowiedzi: 1. The number which is two times greater than 814 is 1612., 2. The number which is four times greater than 815 is 2115., 3. The number which is five times greater than 730 is 116., 4. The number which is seven times greater than 238 is 1658.
Exercise 2
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Wersja alternatywna ćwiczenia: Determine which sentences are true. Możliwe odpowiedzi: 1. The number which is five times greater than 730 is 78., 2. The number which is two times greater than 814 is 68., 3. The number which is four times greater than 815 is 2115., 4. The number which is seven times greater than 238 is 858.
zadanie
Source: GroMar, licencja: CC BY 3.0.
Exercise 3

A person drinks on average 212 of litres during the day. How many litres of liquids does the person drink on average during the standard year, and how many litres during the leap year?

Exercise 4

John’s car on average consumes 612 of litres of petrol per 100. John has travelled 3500 km during the holidays How many litres of petrol did he use?

Describe in English the methods for the multiplication of a mixed number by a natural number.

Exercise 5
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Wersja alternatywna ćwiczenia: Indicate which pairs of expressions or words are translated correctly. Możliwe odpowiedzi: 1. iloczyn - product, 2. liczba naturalna - natural number, 3. liczba mieszana - mixed number, 4. ułamek zwykły - common fraction, 5. ułamek skracalny - irreducible fraction, 6. ułamek nieskracalny - reducible fraction
zadanie
Source: GroMar, licencja: CC BY 3.0.
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Interaktywna gra, polegająca na łączeniu wyrazów w pary w ciągu jednej minuty. Czas zaczyna upływać wraz z rozpoczęciem gry. Jeden ruch to odkrywanie najpierw jednej potem drugiej karty z wyrazem. Każdy wyraz jest odczytywany. Kolejny ruch to odkrywanie trzeciej i czwartej karty. W ten sposób odsłuchasz wszystkie wyrazy. Nawigacja z poziomu klawiatury za pomocą strzałek, odsłuchiwanie wyrazów enterem lub spacją. Znajdź wszystkie pary wyrazów.
Source: Zespół autorski Politechniki Łódzkiej, licencja: CC BY 3.0.

Glossary

product
product

iloczyn

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wymowa w języku angielskim: product
natural number
natural number

liczba naturalna

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wymowa w języku angielskim: natural number
mixed number
mixed number

liczba mieszana

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wymowa w języku angielskim: mixed number
common fraction
common fraction

ułamek zwykły

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wymowa w języku angielskim: common fraction
reducible fraction
reducible fraction

ułamek skracalny

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wymowa w języku angielskim: reducible fraction
irreducible fraction
irreducible fraction

ułamek nieskracalny

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wymowa w języku angielskim: irreducible fraction
multiplication of a fraction
multiplication of a fraction

mnożenie ułamka

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wymowa w języku angielskim: multiplication of a fraction
simplest form
simplest form

najprostsza postać

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wymowa w języku angielskim: simplest form

Keywords

productproductproduct

natural numbernatural numbernatural number

mixed numbermixed numbermixed number

common fractioncommon fractioncommon fraction