Multiplying any 3-digit numbers between 100 and 109

Multiplying any 3-digit numbers between 100 and 109 together is a 3-step simple technique:

Step 1:     Put 1 as the first digit of the answer. It will always be 1.
Step 2:   Add the last digits of each numbers. That’s the next two digits of the answer. If the addition results in a single digit number, make sure to put an extra zero before it.
Step 3:  Multiply the last digits of each number. That’s the last two digits of the answer. Here also make sure to put an extra zero if the product is a single digit number.

Multiplying-numbers-between-100-and-109Example: 107 x 105 =?

    107
X  105
      ?
  1. The first number will always be 1
     107
 x  105 
1####   (1x1 = 1)

  1. Add the last digits of each numbers. 7+5=12. That’s the next two digits of the answer.
      107
  x  105 
 112##   (5+7 = 12)

  1. Lastly, multiply the last digits of each number, 7x5=35
      107
 x   105 
 11,235   (5x7 = 35)

The answer is 11,235.

So, 107 x 105 = 11,235
 
Another Example:

108 × 109 = 11,772

And, 103 × 106 = 10,918



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6 comments

  1. Having read this I thought it was really enlightening.
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    I once again find myself personally spending a significant 
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    ReplyDelete
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