Multiplication Tricks

Magic of Number 1
  • 1 X 1 = 1
  • 11 X 11 = 121
  • 111 X 111 = 12321
  • 1111 X 1111 = 1234321
  • 11111 X 11111 = 123454321
  • 111111 X 111111 = 12345654321
  • 1111111 X 1111111 = 1234567654321
  • 11111111 X 11111111 = 123456787654321
  • 111111111 X 111111111 = 12345678987654321
  • 1111111111 X 1111111111 = 1234567900987654321
Note : Only the leftmost part can have more than one digit. For the rest of the parts, we need to carry over the number preceding the units digit, to the immediate left part , and add it there respectively. Lets see some examples:

Example 1: Lets multiply 11 and 11

STEP 1: No. of digits in multiplier = 2

STEP 2: Write in descending order upto 1. i.e 21[RHS Answer]

STEP 3: Now,No. of digits in multiplier - 1 .ie.(2-1)=1

STEP 4: write it in ascending order upto output of STEP 3.i.e 1[LHS Answer]

STEP 5: Combine STEP 2 and STEP 4 together.i.e 121

Example 2: Lets multiply 1111 and 1111

STEP 1: No of digits in multiplier = 4

STEP 2: Write in descending order upto 1. i.e 4321[RHS Answer]

STEP 3: Now,No. of digits in multiplier - 1 .ie.(4-1)=3

STEP 4: write it in ascending order upto output of STEP 3.i.e 123[LHS Answer]

STEP 5: Combine STEP 2 and STEP 4 together.i.e 1234321

Example 3: Lets multiply 1111111111 and 1111111111

STEP 1: No of digits in multiplier = 10

STEP 2: Write in descending order upto 1. i.e 10/987654321, here carry is generated and it will move forward.[RHS Answer]

STEP 3: Now,No. of digits in multiplier - 1 .ie.(10-1)=9

STEP 4: write it in ascending order upto output of STEP 3.i.e 123456789 + add carry(1)=123456790[LHS Answer]

STEP 5: Combine STEP 2 and STEP 4 together.i.e 1234567900987654321