You will learn to subtract natural numbers using the long method.
Learning effect
You apply long subtraction of natural numbers to do text exercises.
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Revise various methods of mental subtractionsubtractionsubtraction of natural numbersnatural numbersnatural numbers.
Do subtraction using the calculator:
1938 – 1894
1903 – 1867
5003 – 2177
9000 – 678
Think:
Do we always carry calculator with ourselves?
Is it easy to make such calculations mentally?
Task 1
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Open the Slideshow 1 and observe how we perform long subtraction of natural numberslong subtraction of natural numberslong subtraction of natural numbers. After having completed the exercise, present results of your observations.
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Conclusions:
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Long subtraction of natural numberslong subtraction of natural numbersLong subtraction of natural numbers starts with writing numbers under one another, in such a way that ones are under ones, tens under tens, etc. We put a line under the numbers.
Then we subtract ones and write the result under the line, in the place of ones. Then we subtract tens and write the result under the line, in the place of tens, etc.
If in one of the rows the minuendminuendminuend is smaller than the subtrahendsubtrahendsubtrahend, we need to ‘carry’ 1 from the higher row, so that we can do the subtractionsubtractionsubtraction.
Task 2
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Open the Slideshow 2 and observe how we perform long subtraction of natural numberslong subtraction of natural numberslong subtraction of natural numbers if in the minuendminuendminuend occurs zero.
Do the exercises by performing long subtractionsubtractionsubtraction. Give the answers:
a) Tomek got a new book. During first two days he read 150 pages of this book. How many pages does he have left if the whole book has 314 pages?
b) A TV costs 3799 zł and a phone 1560 zł. By how many złoty is the TV more expensive than the phone?
c) In 1683 king Jan III Sobieski won the Battle of Vienna. How many years has passed since that battle?
Talking cards:
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The teacher asks student show to verify solutions of subtractionsubtractionsubtraction without using the calculator. The teacher asks the students to write down the ideas on pieces of paper. The teacher collects them and reads students’ propositions.
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The idea that should dominate:
We can verify the result of subtractionsubtractionsubtraction by doing addition. By adding the differencedifferencedifference to the subtrahendsubtrahendsubtrahend, we should obtain the minuendminuendminuend.
Example:
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Students work in pairs. After having completed the exercises, they exchange notebooks and verify the solutions of their calculations.
Do the calculations using long subtractionsubtractionsubtraction:
7000 – 2623 – 972
5043 – 2654 – 1236
Task 7
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What number should be inserted in the place of * so that the calculation is correct?
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Do the revision exercises.
Remember:
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Long subtraction of natural numberslong subtraction of natural numbersLong subtraction of natural numbers starts with writing numbers under one another, in such a way that ones are under ones, tens under tens, etc. We put a line under the numbers.
Then we subtract ones and write the result under the line, in the place of ones. Then we subtract tens and write the result under the line, in the place of tens, etc.
If in one of the rows the minuendminuendminuend is smaller than the subtrahendsubtrahendsubtrahend, we need to ‘carry’ 1 from the higher row, so that we can do the subtractionsubtractionsubtraction.
Exercises
Exercise 1
Study the information concerning the length of some rivers.
The Vistula river, the longest river in Poland, is 1047 km.
The Volga river, the longest river in Europe, is 3530 km.
The Nile river, the longest river in the world, is 6671 km.
Based on information above, decide if the following sentences are true.
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Exercise 2
Do the subtraction using the long method and verify it by doing the addition:
8844 - 777
2000 - 1212
2345 - 1987
Exercise 3
Create a task that can be solved using the expression 385 – 267.
Do this task and give the answer. Do the exercise in English.
Exercise 4
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Glossary
difference
difference
różnica
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hundreds row
hundreds row
rząd setek
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long subtraction of natural numbers
long subtraction of natural numbers
odejmowanie liczb naturalnych sposobem pisemnym
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minuend
minuend
odjemna
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natural numbers
natural numbers
liczby naturalne
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ones row
ones row
rząd jedności
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subtraction
subtraction
odejmowanie
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subtrahend
subtrahend
odjemnik
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tens row
tens row
rząd dziesiątek
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thousands row
thousands row
rząd tysięcy
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Keywords
differencedifferencedifference – wynik odejmowania
long subtraction of natural numberslong subtraction of natural numberslong subtraction of natural numbers - rozpoczynamy od zapisania tych liczb jedna pod drugą tak, aby jedności były pod jednościami, dziesiątki pod dziesiątkami itd.