Fast Math | Vedic Mental Math Tricks - Multiplication 16 | Don't Memorise

TL;DR

Learn shortcuts for quickly multiplying numbers by 11, 12, 13, and more using simple techniques.

Transcript

this video is going to be a beauty if you know of any shortcuts of multiplication by 11 12 13 and so on please forget those for a while before we move on to the shortcuts we try multiplying 23 with 11 in the normal way we write 23 and then write a 11 under it 23 times 1 is 23 we leave a place here and 23 times 1 again is 20 3 3 5 2 23 times 11 is 2... Read More

Key Insights

• 🍹 Multiplying a number by 11 can be done by writing the first digit as is, summing the first digit with the next digit, and writing the last digit.
• ✖️ The shortcut for multiplying by 12 involves writing the first digit, multiplying the first digit by 2 and adding the next digit, continuing this pattern until the last digit, and multiplying the last digit by 2.
• ✖️ The shortcut for multiplying by 13 is similar to that for multiplying by 12; multiply a digit by 3 and add it to the next digit.
• 🍹 Carrying over is necessary when the sum of two digits in a multiplication is greater than 9.
• #️⃣ The shortcuts for multiplication work for any and every number, including three-digit and four-digit numbers.

Questions & Answers

Q: How can you quickly multiply a number by 11?

To multiply a number by 11, write the first digit as is, sum the first digit with the next digit, and write the last digit.

Q: Does this shortcut work for three-digit numbers?

Yes, the shortcut works for three-digit numbers as well. Write the first digit, sum the first two digits, sum the next two digits, and write the last digit.

Q: Can this shortcut be used for four-digit numbers?

Yes, the shortcut works with any and every number, including four-digit numbers. Follow the same steps as for three-digit numbers.

Q: How do you multiply a number by 12 using the shortcut?

To multiply a number by 12, write the first digit, multiply the first digit by 2 and add the next digit, continue this pattern until the last digit, and multiply the last digit by 2.

Q: What is the purpose of multiplying by 2 in the shortcut for multiplication by 12?

Multiplying by 2 in the shortcut for multiplication by 12 is based on the fact that 12 can be split into 10 + 2. So, multiplying the first digit by 2 accounts for the "2" in 12.

Q: How can you quickly multiply a number by 13?

To multiply a number by 13, multiply a digit by 3 and add it to the next digit. Follow the same pattern until the last digit.

Q: What is the key to understanding and improving multiplication shortcuts?

The key is practice. By practicing and trying out random examples, you can improve your speed and proficiency in using the shortcuts.

Summary & Key Takeaways

• Multiplying a number by 11 can be done by writing the first digit as is, summing the first digit with the next digit, and then writing the last digit.

• The same concept applies to multiplying a number by 12, 13, and beyond. Write the first digit, multiply the first digit by 2 and add the next digit, continue this pattern until the last digit, then multiply the last digit by 2.

• Carrying over is necessary when the sum of two digits in a multiplication is greater than 9.