Math 6 Chapter 1 Lesson 6: Subtraction and division
1. Summary of theory Tóm
1.1. Subtraction of two natural numbers
Generality: a (Subtracted) – b (Minus) = c (Difference)
Given two natural numbers a and b, if there is a natural number x such that b + x = a, we have subtraction a – b = x
VD: 7 (Minus) – 3 (Minus) = 4 (Difference)
1.2. Divisibility and division with remainder
Generality: a (Division) : b (Divisor) = c (Language)
Given two natural numbers a and b, where b \(\ne\) 0, if there is a natural number x such that b. x = a then we say a is divisible by b and we have divisibility a : b = x.
VD: 12 (Divided) : 3 (Divisor) = 4 (Language)
Given two natural numbers a and b where b \(\ne\) 0, we always find two unique two natural numbers q and r such that : a = b . q + r where 0 ≤ r < b.
If r = 0, then we have divisibility.
If r \(\ne\) 0, then we have remainder division.
VD: 14 (Division) = 3 (Division). 4 (Language) + 2 (Remainder) is a division with remainder r = 2.
12 (Division) = 3 (Division). 4 (Land) + 0 (Remainder) is divisible with remainder r = 0.
Conclude:
1. The condition for subtraction is that the subtracted number is greater than or equal to the minus number.
2. A natural number a is divisible by a nonzero natural number b if there is a natural number q such that: a = b. q
3. In division with remainder:
Divisor = Divisor x Quotient + Remainder
a = b . q + r (0 < r < b)
The remainder is always less than the divisor
4. The divisor is always nonzero.
2. Illustrated exercise
Question 1: Do the math: \(2017 – 1892 \) and determine the Subtracted Number, Subtracted Number, Difference
Solution guide:
\(20171892 = 125\)
Where 2017 is the Number to be subtracted
1892 is the minus number
125 is Brand
Verse 2: Do the math: \(175 : 5\) and determine the Divisor, Divisor, and Quotient
Solution guide:
\(175 : 5 = 35\)
Where 175 is the Divisor
5 is the divisor
35 is Beloved
Question 3: Find remainder r in division : \(128 : 3\)
Solution guide:
We have \(128 : 3 = 42 \) remainder 2 So remainder r = 2.
3. Practice
3.1. Essay exercises
Question 1: Do the math: \(2020 – 1890\) and define Subtracted Number, Subtracted Number, Difference.
Verse 2: Do the math: \(1356:3\)and determine the Divisor, Divisor, and quotient.
Question 3: Find remainder r in division: \(2987:9\)
3.2. Multiple choice exercises Bài
Question 1: The condition for the difference \(a – b \) to be a natural number is :
Where a , b are natural numbers
A. a is greater than or equal to b
B. a is greater than b
C.a is less than b
D.a equals b
Verse 2: Perform division: \(159 : 30 \) then how much remainder will we have?
A. 1
B. 3
C. 5
D. 9
Question 3: Find x know : \(27 . x = 108\)
A. 6
B. 5
C. 4
D. 3
Question 4: Given the distance from:
Hanoi – Ho Chi Minh City : 1800km
Hanoi – Da Nang : 800km
Find the distance from Da Nang – Ho Chi Minh City.
A. 1000km
B. 800km
C. 900km
D. 700km
Question 5: We know the divisor is 128, the quotient is 32. So the divisor is equal to ?
A. 3
B. 4
C. 5
D. 6
4. Conclusion
Through this lesson of Subtraction and Division, you need to complete some of the objectives given by the lesson, such as:

Substances of subtraction and division.

Apply properties of subtraction and division to perform calculations.
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