Common sum with number System for class 8

1. Write all possible numbers using the digits 3,6 and 8 without repeating of digits.

Solution:
The numbers are:

3 at unit place: 863,683	Hint: keep 3 at unit place and interchange the position of 8 and 6
6 at unit place:836, 386	Hint: keep 6 at unit place and interchange the position of 8 and 3
8 at unit place:638,368	Hint: keep 8 at unit place and interchange the position of 6 and 3

Question: Do it yourself for 2,4 and 9

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2. How many whole numbers have two digits.

Solution: The two digits whole numbers are from 10 to 99. e.g. 10,11,12......99.
Therefore the two digit numbers= 99-(10-1)
=99-9
=90

Note:Its general formula is : For two digits number = two digits highest number-(two digits lowest number-1)

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3. How many whole numbers have three digits.

Solution: The two digits whole numbers are from 100 to 999. e.g. 100,101,102......999.
We will apply the same formula by changing the numbers of digits only.
Therefore the three digit numbers= 999-(100-1)
=999-99
=900
Used formula is :three digits highest number-(three digit lowest number-1)

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4. What are the greatest and smallest four digits number that can be formed by using the digits 3,0,9,7 without repeating any of the digits in a number?

Solution: The four digits largest number = the digits in descending orders (9,7,3,0)
=9730
The four digits smallest number = the digits in ascending orders (0,3,7,9) but we have to keep smallest digit 3 at the start to make it four digit smallest number otherwise it will become three digits number if it is started with 0.
=3079

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5. Find the difference between smallest 6-digit number and and greatest 5-digit number.

Solution: The smallest 6-digit number=100000
The greatest 5-digit number=99999
difference= 100000-99999
=1 Ans.

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4.Ramesh has enough money for 6 weeks if he spends Rs 1400 per week

4. Ramesh has enough money for 6 weeks if he spends Rs 1400 per week during summer vacation. How long will the money last if he spends Rs 1050 per week?

Solution( By Unitary Method) :

Here we have to find out nos. of weeks. Therefore we will keep the week at right side in the statement.

∵ By spending Rs 1400 per week the money lasts for 6 weeks.

∴ By spending Re 1 per week the money lasts for 6x1400 weeks.	Explanation: For Re 1 per week spending the money will lasts for more numbers of weeks. . Therefore multiplication has been done.
∴ By spending Re 1050 per week the money will last for (6x1400)/1050 weeks.	Explanation:For Rs 1050 per week spending, the money will lasts for less numbers of weeks in comparison to previous spending of Re 1 per week. Therefore division has been done.
= 8400/1050 = 8 weeks Ans.

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3. Eight people eat a stock of food in 30 days. How many people

3. Eight people eat a stock of food in 30 days. How many people will consume the stock of food in 20 days?

Solution( By Unitary Method) :

Here we have to find out nos. of people. Therefore we will keep the people at right side in the statement.

∵ In 30 days a stock of food is eaten by 8 people.

∴ In 1 day same stock of food will be eaten by 30x8 people.	Explanation: For 1 day more nos. of people will be needed to eat the same stock of food. Therefore multiplication has been done.
∴ In 20 days same stock of food will be eaten by (30x8)/20 people.	Explanation: For 20 days lesser nos. of people will be needed to eat the same stock of food. Therefore division has been done.,/p>
= 240/20 = 12 people Ans.

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2. if 20 men can complete a job in 4 days. How many men

2. if 20 men can complete a job in 4 days. How many men will be required to finish the work in 40 days?
Solution:

Suppose x men will be required to complete the job in 40 days

∵ To complete a job in 4 days the required men are 20 .

∴ To complete the job in 1 day the required men are 20x4 .	( explanation: in 1 day more men will be needed to complete the same job, therefore for more men multiplication has been done.)
∴ To complete the job in 40 days the required men are (20x4)/40 .	explanation:lesser number of men will be needed to complete the job in 40 days in comparison to one day. Therefore division has been by 40
= 80/40 = 2 men Ans.

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1.Three men do a job in 8 days. How long will 4 men

1.Three men do a job in 8 days. How long will 4 men take to finish the job?

Solution( By Unitary Method) :

Here we have to find out days. Therefore we will keep the days at right side in the statement.

∵ 3 men complete the job in 8 days

∴ 1 men complete the job in 3x8 days.	( explanation: one man will take longer to complete the same job, therefore for more days multiplication has been done.)
∴ 4 men complete the job in (3x8)/4	explanation: 4 men will take lesser time to complete the same job in comparison to 1 man, therefore for less days division by 4 has been done.
= 24/4 , = 6 days Ans.

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Difference Between O and Au Matra | ओ और औ की मात्रा मे अंतर समझना

Difference between these two Matra (मात्रा) can be understood by reading and writing practice.

For this a list of few simple words of o (ओ) and Au (औ) Matra atra (मात्रा) is given here. After that you are advised to watch the video.

Search online Hindi writing editor in google . You will find two or three efficient editor to write Hindi with keyboard. This will help to ask question in the comment box.

Here is the list of word. You should write these words with the help of someone who can dictate you.

ओ की मात्रा वाले शब्द	औ की मात्रा वाले शब्द
ओक ओत चोट चोंच चोआ चोखा चोकर पोंछ पोआना पोखरा पोछना पोटना मोंगरा मोछ	कील और औत चौका चौटाला चौका चौखट चौकीदार पौना पौरक पौनार मौज मौन सौरव गौरतलब तौल

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