Japanese Multiplication and Quick Methods

The video tutorial covers various math tricks for multiplication and subtraction. It starts with using fingers to multiply numbers by 9, then moves to multiplying large numbers by 9 using a simple subtraction method. The Japanese multiplication method is introduced for visualizing and calculating products of large numbers. Tricks for multiplying by 11, 15, and 30 are explained, along with a method for finding percentages of round numbers. The video also covers multiplication as repeated addition, subtracting from 1000, memorizing Pi, and multiplying numbers in the 90s.

How can you multiply 3 by 9 using your fingers?

• Bend the ninth finger and count the unbent fingers.

• Bend the first finger and count the unbent fingers.

• Bend the third finger and count the unbent fingers.

• Bend the fifth finger and count the unbent fingers.

What is the quick method to multiply 1250 by 9?

• Add 1250 to itself nine times.

• Multiply 1250 by 10 and subtract 1250.

• Add a zero to 1250 and subtract 1250.

• Divide 1250 by 9 and multiply by 10.

In the Japanese multiplication method, what do the diagonal lines represent?

• The number of tens and ones in each number.

• The sum of the numbers being multiplied.

• The number of hundreds in each number.

• The difference between the numbers being multiplied.

How do you handle double-digit results in the Japanese method?

• Add the tens digit to the result.

• Transfer the tens digit to the next column.

• Subtract the tens digit from the result.

• Ignore the tens digit.

What is the first step in multiplying 322 by 14 using the Japanese method?

• Subtract 14 from 322.

• Add the numbers together.

• Draw diagonal lines for 322 and 14.

• Multiply 322 by 10.

How do you multiply 34 by 11 quickly?

• Subtract 11 from 34 and multiply by 10.

• Multiply 34 by 10 and add 34.

• Separate the digits and insert their sum in between.

• Add 34 to itself 11 times.

What is the method to find 30% of 80?

• Multiply 30 by 80 and divide by 100.

• Multiply the tens digits of 30 and 80.

• Subtract 30 from 80 and multiply by 10.

• Add 30 and 80 and divide by 2.

How do you multiply 64 by 15 using a quick method?

• Add a zero to 64, divide by 2, and add the results.

• Add 64 to itself 15 times.

• Multiply 64 by 10 and add 64.

• Subtract 15 from 64 and multiply by 10.

What is the concept of multiplication as repeated addition?

• Multiplying is the same as subtracting a number multiple times.

• Multiplying is the same as multiplying a number multiple times.

• Multiplying is the same as adding a number multiple times.

• Multiplying is the same as dividing a number multiple times.

How do you subtract 578 from 1000 using a simple trick?

• Subtract each digit from 9, except the last from 10.

• Subtract each digit from 10.

• Subtract each digit from 8.

• Subtract each digit from 7.