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Lesson Posted on 16 Jan Tuition Exam Coaching/Quantitative Aptitude

Three Digit Multiplication Shortcut

Mahadev

Looking to teach and guide students to achieve in competitive exams be it ssb, rrb, upsc, po, clerks...

1) 123*456 I II III 1 2 3 4 5 6 Multiply column III. Here, it's 18. Write 8 and carry over 1. Result=>__8 Cross multiply column II and III diagonally. ie 2*6 and 3*5. We get 12 and 15 respectively. Add both, you'll get 27. Add the carry over from previous step. So 28 is what we get.... read more

1) 123*456

I II III

1 2 3

4 5 6

- Multiply column III. Here, it's 18. Write 8 and carry over 1. Result=>__8
- Cross multiply column II and III diagonally. ie 2*6 and 3*5. We get 12 and 15 respectively. Add both, you'll get 27. Add the carry over from previous step. So 28 is what we get. Write 8 and carry over 2. Result=>__88
- Now we need to cross multiply I and III diagonally like the previous step and multiply column II. Add up all the three numbers. 1*6+3*4+2*5=28+2(carry over from previous step)=30. Write 0 and carry over 3. Result=>__088
- Now cross multiply I and II and add the resultant numbers. 1*5+2*4=13+3(carry)=16. Write 6 and carry over 1. Result=>__6088
- Finally, multiply column I. 1*4=4+1(carry)=5 Result=>56088

2) 123*456

I came up with this one myself. lol I find this easier than the vedic math shortcut above.

hundreds tens ones

100 20 3

400 50 6

- I've just written the place value of each digit.
- Take 100 and multiply with all three places of the second number. (100*400=40000)+(100*50=5000)+(100*6=600)=45600
- Take 20 and repeat. (20*400=8000)+(20*50=1000)+(20*6=120)=9120
- Take 3 and repeat. (3*400=1200)+(3*50=150)+(3*6=18)=1368
- Add all three results=> 45600+9120+1368=56088.

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Comments Answered on 01/11/2017 Exam Coaching/Quantitative Aptitude

Diwakar Ramachandra

Language, Aptitude, Employability and Soft Skills Trainer

Arun

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Answers 5 Comments Answered on 24/11/2017 Exam Coaching/Quantitative Aptitude

Which is the best resource for quantitative aptitude for a beginner?

M siva rama krishna

Maths Tutor

Quantitative aptitude by arun sharma

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Answers 3 Comments Looking for Quantitative Aptitude Coaching

Find best Quantitative Aptitude Coaching in your locality on UrbanPro.

Answered on 02/11/2017 Exam Coaching/Quantitative Aptitude

What is the remainder of 56*32/5?

Shravan

In 56, 5's are 11 and 1/5 gives .2 so 11.2*5 gives 55 1 =56

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Answers 3 Comments Answered on 20/11/2017 Exam Coaching/Quantitative Aptitude

What is the best book for quantitative aptitude for the IBPS clerk exam?

Coaching Classes By Preeti Sikka

Rs aggarwal for aptitude is good book for aptitude of all exams. Is any specific topic for particular exam is not in the book,then for that topic you can search separately.

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Answers 1 Comments Answered on 01/11/2017 Exam Coaching/Quantitative Aptitude

What is the remainder of 1x1! +2x2! +3x3! +?+100x100! When divided by 202? (2! =2factorial=2x1)

Mathivanan Palraj

CAT/GMAT Expert

Rewrite the terms: (2-1)*1!+(3-1)*2!+..........+(101-1)*100!= 101!-1! When this is divided by 202, the remainder is -1, which implies the remainder is 201.

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Answers 1 Comments Looking for Quantitative Aptitude Coaching

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Answered on 05/11/2017 Exam Coaching/Quantitative Aptitude

What is the remainder when 39^42 is divided by 10?

Vibhor Jain

As the whole number is divided by 10 so we need to look only at the units digit of the number i.e. 9^42. As powers of 9 has a cyclicity of 2 meaning odd power of 9 will give 9 as the units digit while even power will give 1. As 9 is raised to power 42 which is even means that the units digit of the... read more

As the whole number is divided by 10 so we need to look only at the units digit of the number i.e. 9^42. As powers of 9 has a cyclicity of 2 meaning odd power of 9 will give 9 as the units digit while even power will give 1. As 9 is raised to power 42 which is even means that the units digit of the number will be 1. And 1 ÷ 10 =1 So (39^42)÷10 gives '1' as remainder, which us the desired answer. read less

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Answers 2 Comments Answered on 03/11/2017 Exam Coaching/Quantitative Aptitude

Does dividing a^(b-1) by b always give 1 as the remainder?

Mathivanan Palraj

CAT/GMAT Expert

Let a=2; b=9; then 2^8=256. When this is divided by 9, the remainder is 4.

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Answers 1 Comments Answered on 03/11/2017 Exam Coaching/Quantitative Aptitude

If (1+9+99+999+9,999+99,999+999,999) ² is divided by 10, what would the remainder be?

Mathivanan Palraj

CAT/GMAT Expert

The unit digit of the term is 5. Hence, the remainder is 5.

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Answers 1 Comments Looking for Quantitative Aptitude Coaching

Find best Quantitative Aptitude Coaching in your locality on UrbanPro.

Answered on 04/11/2017 Exam Coaching/Quantitative Aptitude

Is there any order in which to prepare the aptitude topics well for a weak student?

Shashank Ranjan

Math Expert

Latest.

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Answers 2 Comments UrbanPro.com helps you to connect with the best Quantitative Aptitude Coaching in India. Post Your Requirement today and get connected.

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