Abhishek R

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  • in reply to: I am Qian Hong, nice to meet you!!! #12739
    Abhishek R
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    What kind of mental math do you do in school?

    The reason I am asking is to know whether the book and the course has everything that you do in school.

    Will include additional content based on your feedback.

    in reply to: I am Qian Hong, nice to meet you!!! #12737
    Abhishek R
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    Wow QianHong.

    Where are you from?

    Would definitely love to hear more about the things that are tested in eagle flight team club.

    Please share your techniques here with the community.

    in reply to: How to find the factors of large numbers fast #12128
    Abhishek R
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    You make the number smaller by dividing by prime numbers first 2, 3, 5, 7 and 11. 

    Mostly it will reduce the number unless its a prime number or a multiple of a prime number greater than 11

    506 divided by 2 gives 253. 

    253 cannot be divided by 3,5 or 7. How do I know its not divisible so quickly? I use the divisibility test.

    A number is divisible by 2 if the last number is even. 
    A number is divisible by 3 if the sum of the digits is divisible by 3
    A number is divisible by 5 if the last digits are 0 or 5. 
    For 7 you need to actually divide to check. 
    So we try 11. 

    253 divided by 11 gives 23
    23 is also a prime number so we can’t reduce it further. 

    This is the only way to reduce it.
     
    You can combine the prime factors together if you want to reduce steps. 
    For example, the prime numbers of 506 is 2, 11 and 23. 
    We can combine 2 and 11 to get 22.
    So we are left with 22 x 23. 

    Hope this helps

    in reply to: Hello #11630
    Abhishek R
    Keymaster
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    Welcome to the community Jim. How far into the book are you right now?

    in reply to: getting most out of me. #11113
    Abhishek R
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    Hi Toni,

    Any goal you hope to achieve by inculcating this new habit? Like a specific grade or something?

    in reply to: building daily study and healthy habit. #11104
    Abhishek R
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    Hi Toni,

    Welcome to the community. Looking forward to seeing your progress updates. Please make sure you complete all the workbooks and post it here.

    Abhishek

    in reply to: getting most out of me. #11103
    Abhishek R
    Keymaster
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    Hi Toni

    What do you spend time learning? Is it school or university work or some new skill?

    Abhishek

    Abhishek R
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    Ah very useful indeed. If you notice your steps, you are converting the single digit multiplication problem into another multiplication problem 4 x 6 = 24. I would therefore recommend learning the single digit multiplication table by heart.

    in reply to: DS, DD of large negative numbers #10776
    Abhishek R
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    The method is the same for negative and positive numbers. There is absolutely no difference.

    in reply to: Do you have a facebook group to accompany your book? #10531
    Abhishek R
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    Currently there is no Facebook group. We only have the community forum here on the website.

    in reply to: purchasing the video course and the book #10394
    Abhishek R
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    The $45 price includes a 30% discount.

    The current price on Udemy is $65 – https://www.udemy.com/course/speed-mental-math-tricks/

    You can purchase the course at $45 from Ofpad.com – https://ofpad.com/mental-math-sp/

    Unfortunately we cannot discount the course any further to be fair to people who paid full price.

    in reply to: multiplying 4 digits by 11 with carry over numbers #10393
    Abhishek R
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    The steps are the same as 3 digit multiplication by 11.

    Here is an example of 4 digit multiplication.

    5763 x 11

    The first digit becomes the first digit of the answer

    5763 x 11 = 5 _ _ _ _

    Adding the next two digits 5 + 7 gives 12. The second digit 2 in 12 becomes the second digit of the answer.

    5763 x 11 = 5 2 _ _ _

    Since 12 has two digits, we carry over the first digit 1 so 5 becomes 6.

    5763 x 11 = 6 2 _ _ _

    Adding the next two digits 7 + 6 we get 13. The second 3 in 13 becomes the third digit of the answer

    5763 x 11 = 6 2 3 _ _

    Since 13 has two digits, we carry over the first digit 1 so 2 becomes 3.

    5763 x 11 = 6 3 3 _ _

    Adding the next two digits 6 + 3 we get 9 which becomes the next digit of the answer.

    5763 x 11 = 6 3 3 9 _

    The last digit 3 becomes the last digit of the answer.

    5763 x 11 = 6 3 3 9 3

    Let me know if this example clarifies.

    in reply to: DD Method #8961
    Abhishek R
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    Hi Jaggari,

    The first digit left of the decimal is odd and you alternate between odd and even.

    For example, let us take 7324.

    So the first digit left of the decimal is 4. So it becomes Odd (O)
    O
    7 3 2 4

    Now you alternate between Odd (O) and Even (E)
    E O E O
    7 3 2 4

    Hope this clarifies.

    in reply to: Suggestions and Questions about the Book #8909
    Abhishek R
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    Hi Aaron,

    The round up method simply states that the last digits add up to 10 and the other digits add up to 9. There is no concept of left to right or right to left here. So was not sure what you meant?

    Can you give me an example of what kind of scenarios you will need to do mental math for trigonometry or geometry? Those are generally not areas where we need to do mental math in the real world or in exams.

    Multiplying large numbers come with practice and using the mind palace. You have to use a combination of rounding up and the methods we have covered to do the mental calculation. It will not be as easy and fast as multiplying lower digit numbers.

    in reply to: Rounding up #8897
    Abhishek R
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    You don’t always have to make all numbers add up to 9.

    The number of digits the rounded-up value will have will depend on how much you round up to.

    If you round up 3898 to 10,000 you would have rounded up by 6102 which has 4 digits.
    If you round up 3898 to 4,000 you would have rounded up by 102 which has 3 digits.
    If you round up 3898 to 3,900 you would have rounded up by 02 which has 2 digits.

    So in this scenario, you shouldn’t do the addition of 3 + 4 + 2 = 9.

    Let me know if this clarifies.

    When you round up 3898 to 4000 you will have to add a 3 digit number to 3898 to get 4000. So you don’t have to add the 3 + 4 + 2 to get 9.

    The amount you round up will have one digit lesser than the original numbers.

    Both 3898 and 4000 are 4 digit numbers so the amount you have to round up has to be a 3 digit number which is 102.

    How many numbers

Viewing 15 posts - 31 through 45 (of 73 total)