Doing Math fast can work magical wonders on your kids. This is especially true when they appear for competitive exams or Math Olympiads. What do you think the tricks are? Summing up, subtracting and multiplying numbers faster than your peers can help you crack high school Math examinations in a hassle-free manner.
Table of Contents
- How do you add large numbers?
- Subtraction made easier
- Multiplication tricks
- Discover quirky tricks for a division
- Multiplication of 9- made easy
- Explore 10 and 11 tricks
- Multiplying large numbers
- Multiplying numbers that end with 0
How do you add large numbers?
Adding larger numbers can be difficult while you try doing on your head. You are unable to derive the right answers by doing mental math. This is a simplified method wherein adding larger numbers become a piece of cake. You need to convert the given numbers into multiples of ten. How do you calculate 644 + 238?
Just round them off to their nearest tens. Add up 650+ 240= 890. Now how is 650 > than 644? 650-644= 6. How is 240 > than 238? 240-238= 2. Add up the resulting figures, i.e., 6 and 2. You get 8. Now take the rounded-off number. The number is 890. Subtract 890 with 8. The resulting number is 882. Henceforth, 644+238= 882.
You can apply for online math tutor jobs. But before that, you need to enhance your knowledge of Mental Maths or what is known as Vedic Maths. You can add, subtract, multiply and divide complex numbers at a fraction of a second.
Subtraction made easier
This is the ground rule to subtract a large number from 1000. How do you derive the answer for 1000-556? Subtract every digit from 9 excepting the last digit. The last digit is subtracted from 10.
The first digit of 556 is 5. Subtract 5 from 9. Or what is 9-5? The answer is 4.
The second digit of 556 is again 5. 9-5=4.
The last digit of 556 is 6. You must subtract 6 from 10. In other words, 10-6= 4.
Henceforth, 1000-556= 444. When you get the logic right, you can apply the same logic everywhere. The results will be surprisingly accurate every time. That is the beauty of Math.
Learn Maths Online
For multiplying an even number by 5, there is a very simple trick you can make use of. What is the number you are planning to multiply five? Is it 5X 4?
Take the number to be multiplied with 5. The number is 4. There are two steps here to help you arrive at the result.
- Cut the number by half. 4/2= 2.
- Add a zero to the resulting number. The resulting number is 20. Hence, 5*4= 20.
You have a different formula when you multiply an odd number with 5. What is 5*3= You know it is 15. But let us apply the trick to arrive at the answer. The steps are given to you in a bulleted form.
- Subtract one from the number you intend multiplying with 5. 3 becomes 2.
- Now half the number that has arrived. Two becomes 1. That becomes your first digit.
- Add 5 to the last digit.
- 3*5= 15. You can apply the same formula, which multiplying larger even numbers or odd numbers with 5.
Discover quirky tricks for a division
These are easy steps to analyze if certain numbers are evenly divisible or not. The points are illustrated for you in the form of bullets.
- Any given number is evenly divisible by 10 if the number ends with a 0.
- A number is divisible by 9 when you add the digits of the given number. The resulting number must be a direct factor of 9. You take 27, for instance. 2+7=9. 9 is directly divisible by 9. Take another number. 1422. Add 14+2+2. The resulting number is 18. 18 is a multiple of 9. 9*2=18. Hence, 1422 is evenly divisible by 9.
- A number is evenly divisible by 8 if the last three digits are evenly divisible by 8. Or if the last three numbers are 000.
- A given number evenly divides with 6 when you add the digits, and the resulting number is evenly divisible by 3.
- You can say that a given number is evenly divisible by 5 when you have the number ending with 0 or 5.
- For even divisibility with 4, check if the last two digits evenly divide with 4. Else look if the number ends with a 00.
- Even the divisibility of 3 again is calculated while you all the digits of the number. The resulting figure needs to be a multiple of 3.
- Divisibility for two holds good for numbers ending with a 0,2,4, 6, or 8.
Multiplication of 9- made easy
You can easily multiply the number 9 by any other number with this method. Here is the trick for getting your answers right. Suppose you have 9 X 5
What is the number you are multiplying with 9? It is 5. Subtract 1 from 5. You get 4.
Now 4 is the first digit. Subtract 4 from 9. You get 5. Thus 9*5= 45. This way, you can trick people multiplying numbers with 9.
Explore 10 and 11 tricks
To multiply a number by 10, it is simple and easy. You just add a zero next to the number. For example, 82 X 10= 820.
For multiplying numbers with 11, here goes the trick. What is 25 * 11? Take 2 as the first digit. And 5 is the last digit. What is the middle digit? Simple – just add 2 and 5. What is 2+5? 2+5=7. So, 25 X 11= 275.
If the numbers at the center add up to a number with two digits, insert the second number. You can add 1 to the first one. What is 88*11?’
8+1_8+8_8, which is 968. You can log on to some of the best
Multiplying large numbers
What is 20 X 120?
You derive the answer in three simple steps.
- Take the first number. This is 20. Half the first set number. You get 10.
- Now, double the second set. 120 becomes 240.
- Multiply the answers together. What is 10* 240? You get 2400. The answer for 20*120= 2400.
When you take up the job of a math tutor online, you can brief your students with these tips and tricks. This way, your students wouldn’t waste time on calculating numbers, percentages, etc.
Multiplying numbers that end with 0
We had seen the divisibility test for number 10. You had seen this in the earlier paragraph. You can apply the same rule while multiplying larger numbers ending with zeroes. What is 200 * 400?
The answer can arrive within 4 simple steps.
- Multiply 2*4. In other words, 2 X 4= 8
- Count the number of zeros in 200. These are two zeroes at the end.
- Again, count the number of zeros in 400. You have two zeroes in 400 too.
- Now take 8 as the first digit and add all the four (Two zeroes in 200 and two zeroes in 400) zeroes. Hence, 200 X 400= 80000
Now that you know what the tricks for doing maths quick go right ahead and start implementing them. If you are looking for additional help, do check out the video tutorials, or the study material available online at Study Spectrum. Do you know that you can even hire a tutor online to improve your mathematics skills? Register at www.studyspecturm.com today and avail of the numerous benefits it provides.