# Math Tricks : Multiplication Tricks

January 04, 2017

**Multiplication Tricks | Mathjokes.net**

This amazing math tricks can be used to multiply numbers instantly.

It is important to remember that for this particular multiplication trick that it is just that - it is very specific and has a few conditions which must be met in order for it to work.

## Multiplication Trick #1: Ignore the trailing zeros

multiplication tricks |

If you have a trailing zeros, forget about it. What this means is that if you have a number such as 690000, pretend it is just 69. Once you do the multiplication, you just add the zero back to the end of your answer. This works for any number of zeros. 690, 690000, and 690000000 should all be treated the same as 69. Just remember to add the respective amount of zeros to the end of your answer.

However, you cannot simplify a problem when the zeros are in the middle. You can only use this for trailing zeros (zeros at the far right side). For example, 609 must be thought of as 609. This cannot be reduced to anything smaller. On the contrary, 609000 can be treated as 609, because there was one trailing zero. This helps quite a bit.

## Multiplication Trick #2: Ignore the decimals

This is like the first one multiplication trick. If you have a decimal, forget about it. Pretend there is no decimal. If you have a number such as 6.9, pretend it is just 69. 6.95 becomes 695, and 45.6 becomes 456. It is as simple as that. Now, how does this affect the answer? You need to count the number of digits that come after the decimal. 45.6 has 1 digit after the decimal, and 6.95 has 2 digits after the decimal. You are multiplying two numbers together, so you add the total. If you were multiplying 45.6 and 6.95, there are 3 total digits that come after the decimal. This should be reflected in your answer. If there is a total of 3 digits after the decimals, you will place the decimal in your answer so there are 3 digits after the decimal! It's multiplication trick as simple as that.For example, if you have a number that is 2.34 multiplied by 56.789, the answer will be in the form xxx.xxxxx.

## Multiplication Trick #3: Round And Adjust

**Example 1**:

Let’s say I want to multiply 97 by 53. First I rounded, did the multiplication, and then adjusted my result. I rounded 97 up to 100. Then, it is extremely easy to multiply 100 by 53: 5300. Then, I think about how much I rounded by. I rounded up by 3. 100 x 53 is 3 x 52 more than 97 x 53.

This means, that 97 x 53 = (100 x 53) - (3 x 53). Therefore, I find a quick answer by multiplying 100 by 53, then I subtracted 3 times 53 from that. 3 times 53 is 159. 5300 – 159 is 5141.

**Example 2**:

What is 83 times 16? 83 is close to 80, so let’s start with that. 80 times 16 is like 8 times 16. 8 times 16 is 128. Since I turned 80 into 8, I’ve got to add a zero to the end. 1280. I rounded down by 3, this means that I now have to add this 3 back in. To do so I multiply 3 by 16, and add this to my answer. 3 times 16 is 48, and 1280 + 48 is 1328.

Or we can write: 83 x 16 = (80 + 3) x 16 = (80 x 16) + (3 x 16).

This multiplication trick took a little while to read, but it goes much faster in your head once you understand the method.

Remember: For this multiplication trick you can only round ONE of the numbers. Do not round both numbers.

## Multiplication Trick #4: Multiply In Parts

Basically, it is very similar to round and adjust method, but it does not require rounding or adjusting. It is simply breaking down a number piece by piece.

**Example:**

73 x 45 = ? First 7 x 45 is 315, and 3 times 45 is 135. The answer is simply 3150 + 135. The extra zero on the 3150 was inserted because the 7 is really a 70. The answer is just 3285.

## Multiplication Trick #5: Multiplication of 2 and 3 Digit Numbers

Condition which must be met in order for it to work:Select any two numbers and deduct the rightmost digits, i.e., 'unit digit' from both the numerals. The results derived after subtraction of the numbers from unit digits should be 'Equal'.

### Multiplication trick of two digit numbers

**Example:**

33 x 36 = ?

**Step 1**: Choose the unit digit of both the numerals and deduct it from the given numerals.

33 - 3 = 30

36 - 6 = 30

**Step 2**: Now, select any one number (33) and add it with unit digit of another number(6)

33 + 6 = 39

**Step 3**: Multiply the result obtained in step 1 and step 2.

39 x 30 = 1170

**Step 4**: Multiply the unit digit values.

3 x 6 = 18

**Step 5**: Finally, add values obtained from step 3 and step 4.

1170 + 18 = 1188

33 x 36 = 1188.

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### Multiplication trick of three digit numbers

**Example:**

504 x 509 = ?

**Step 1**: Deduct the last digit from the respective numerals.

504 - 4 = 500

509 - 9 = 500

**Step 2**: Pick any one number and add it with the unit digit of another number.

504 + 9 = 513

**Step 3**: Multiply the result obtained in step 1 and step 2.

513 x 500 = 256,500

**Step 4**: Multiply the unit digits of the given numbers.

4 x 9 = 36

**Step 5**: Add the values obtained in step 4 and step 5.

256,500 + 36 = 256,536

504 x 509 = 256,536.

Do you have any cool multiplication tricks of your own? Let us know in the comments section.