Fast Mental Multiplication Trick - Multiply in your head using base 20 and 30

TL;DR

Learn how to use base method multiplication to quickly multiply numbers in the 20s and 30s mentally.

Transcript

good day and welcome to the tech math Channel what we're going to be having a look at in this video is we're going to be looking at using base method multiplication to multiply numbers in their 20s and 30s this is sort of part two we had a video before where we were looking at uh using base method multiplication for um multiplying numbers more arou... Read More

Key Insights

• ⚾ Base method multiplication simplifies the multiplication of numbers in the 20s and 30s by using a base to aid calculations.
• 😵 Cross addition is a technique that helps determine the adjusted answer.
• 🌥️ The base is considered when multiplying, resulting in a larger answer.
• ⚾ Subtracting is necessary when the numbers are below the base.
• ❓ Mental calculations can be done once the concept is understood and practiced.
• ⚾ Base method multiplication is a powerful technique for mental math calculations.
• ❓ The technique can be extended to bases other than 10, such as 20 or 30.

Questions & Answers

Q: What is base method multiplication?

Base method multiplication is a technique that simplifies multiplication by using a third number called a base. It is especially useful for multiplying numbers in the 20s and 30s.

Q: How does cross addition work in base method multiplication?

Cross addition involves adding the numbers' distance from the base together. For example, if we have numbers 23 and 25 with a base of 20, we add 3 and 5 to get 8, which becomes the first part of our answer.

Q: How do we adjust the answer considering the base in base method multiplication?

If the base is twice as big as the base (e.g., 20 being twice as big as 10), we double the cross addition answer. If the base is three times as big (e.g., 30), we triple it. The multiplied numbers are then added to the adjusted answer.

Q: Can base method multiplication be done mentally?

Yes, once you understand the concept, you can perform base method multiplication mentally. Practice is key to becoming proficient in mental calculations.

Summary & Key Takeaways

• Base method multiplication involves using a third number, called a base, to simplify the multiplication of two numbers. This method is useful when multiplying numbers in the 20s and 30s.

• By identifying the numbers' distance from the base (10, 20, or 30), the cross addition technique is used to find the answer.

• The base is taken into account when multiplying, resulting in a larger answer. Subtraction is used when the numbers are below the base.