Today I am going to share quick multiplication tricks that will help you find the solution within 20 seconds. Must read - 10 Coolest Maths tricks

### Multiply by 9,99,999,etc...

56*99=5544

Step 1:Place a zero at the end for each 9 :5600

Step 2 : Subtract the original number from Step 1 like this 5600-56=5544

### Multiply by 125

**68*125=8500**

Step 1 :Place three zeros at the end of the number :68000

Step 2: Divide the number from Step 1 by 8:68000/8=8500

64*125 is the same as :

32*250 is the same as

16*500 is the same as

8*1000

**64*125**

Step 1. Each time you just need to pick 125 multiply it by 8 will get 1000

Step 2. Pick 64 and divide it by 8 will get 8

Step 3. Multiply the results with each other 8* 1000

Hence Solution is 8000

[Hint: Just remember 125*8=1000]

### Multiply two digits numbers ending in 1

**51*31=1581**

Step 1: Multiply the left most digits : 5*3=15

Step 2: Add the left most digits:5+3=8

Step 3: Places the result from Step 2 next to the result from Step 1:158

Step 4 : Places 1 next to the result from Step 3 : 1581

### Multiply numbers between 11 and 19

**14*18=252**

Step 1: Add the larger number to the right most digit of the other number:18+4=22

Step 2: Put a 0 at the end of the result from step 1:220

Step 3 :Multiply the right most digits of both original numbers : 8*4=32

Step 4:Add Step 2 and step 3 :220+32=252

### Multiply two digit number by 11

**53*11=583**

Step 1: Add the both digts of the two digit number:5+3=8

Step 2: Place the result in between both digits : 583

**59*11=649**

Step 1: 5+9=14

Step 2 : Carry the 1 when the result is greater than 9:5+1=6

Step 3: 649

### Multiply by 5

**1234 *5 =6170**

Step 1 : Divide the number by 2 :1234/2=617

Step 2: Multiply the result from Step 1 by 10 : 617*10=6170

Step 1: Divide the number by 4:18/4

Step 2: Multiply the number from Step 1 by 100: 4.5 * 100 = 450

### Multiply by 25

**18*25=450**Step 1: Divide the number by 4:18/4

Step 2: Multiply the number from Step 1 by 100: 4.5 * 100 = 450

### Multiply by 9

**56*9=504**

Step 1: Multiply the number by 10: 56*10=560

Step 2: Subtract the original number from Step 1: 560-56=504

### Factorization

By Factoring number,you can break down problems into simpler multiplication tasks.Also,you may be able to apply some techniques you learned.

**21*33**

step 1 : 21*11*3

Step 2: 231*3

Step 3 :693

**67*81**

Step 1: 67*9*9

Step 2:603*9=5427

**28*125=3500**

Step 1: 28*125

Step 2: 28*25*5

Step 3:28*(100/4)*5

Step 4:28/4*100*5

Step 5:7*500=3500

### Some Special type

#### When sum of unit digit is 10 and remaining digit is same.

**43×47 = 4 × ( 4+1 ) / 3×7**

= 4×

^{5}/21
=

Ans = 2021

=

Ans = 5616

= 10 ×

=

Ans = 11024

^{20}/21Ans = 2021

**72×78 = 7×8 / 2×8**=

^{56}/16Ans = 5616

**104 × 106 = 10× ( 10+1 ) / 4×6**= 10 ×

^{11}/24=

^{110}/24Ans = 11024

#### When sum of ten's digit is 10 and unit digit is same

**46 × 66**

= ( 4×6 ) +6 / 6×6

= 24 +

^{6}/36

=

^{30}/ 36

Ans = 3036

**83 × 23**

= ( 8×2 ) +3 / 3×3

=

^{19}/09

Ans = 1909

**92 × 12**

= ( 9×1 ) + 2/2 × 2

=

^{11}/04

Ans = 1104

#### When unit digit is 5 in both the numbers and difference between both number is 10.

**75 × 65**

=

^{48}/75

Ans = 4875

**45 × 35**

= 3 × ( 4+1 )/75

= 15 /75

Ans = 1575

**105 × 95**

= 9 × ( 10+1 ) / 75

= 99/75

Ans = 9975

####
**Find the unit digit of 147**^{128 }* 138^{148} ?

^{128 }* 138

^{148}?

### Updated on 12th October 2015

### Multiply by 11,111,1111....so on

**Ques 1. 111111111 ✘ 111111111 = ?**

**Sol:**

No of digits in multiplier = 9

Write in ascending order from left side like this:

987654321

and now 9-1=8

write it in descending order just after it

12345678

now you will get like this:

12345678987654321

hence

111111111✘111111111 = 12345678987654321

**Ques 2. 1111111111 ✘ 1111111111 = ?**

**Sol:**

No of digits in multiplier =10

Write in ascending order from left side like this:

10 9 8 7 6 5 4 3 2 1

and now 10-1=9

write it in descending order just after it

1 2 3 4 5 6 7 8 9

and after it just add

**the**

**carry**

1 2 3 4 5 6 7 8/ 9/

**10**9 8 7 6 5 4 3 2 1

8+1/ 9+1 / 0

1 2 3 4 5 6 7 9 0 0 9 8 7 6 5 4 3 2 1

now you will get like this:

1234567900987654321

hence

1111111111✘1111111111 = 1234567900987654321

**Ques 3. 1111111✘2222222 = ?**

**Sol:**

No of digit in the multiplier is 7 then let n=7;

Now Just multiply the digit 2 from 1 to 7 time & arrange them from extreme left to right in ascending order,you will get like this:

14 12 10 8 6 4 2

and now just subtract one from n.like this n=7,so n-1=6.

Multiply the digit 2 from 1 to 6 time & arrange them from just right after it,you will get like this:

2 4 6 8 10 12

Now placing both outcome like this & add the carry

2 4 6 8

**10 12 14 12 10**8 6 4 2

8+1/0+1/2+1/4+1/2+1

You will get the answer:

2 4 6 9 1 3 5 3 0 8 6 4 2

**Ques 4. 1111111✘5555555 = ?**

**Sol:**

No of digit = 7

Now Just multiply the digit 5 from 1 to 7 time & arrange them from extreme left to right in ascending order,you will get like this:

35 30 25 20 15 10 5

Just right after it perform same action but in descending order & till 6 times only.like this:

5 10 15 20 25 30

Now placing together ,just add the carry

5 10 15 20 25 30 35 30 25 20 15 10 5

6 1 7 2 8 3 8 2 7 1 6 0 5

1111111✘5555555=6172838271605