Fun With Number 5

Rule:The trick that we are going to learn this week is normally used for multiplication and in this case for both the numbers, the digits in the unit's place i.e. the last digits are 5. Also, the first digits are same. You will understand this as you see some examples. 25 x 25 = 6 | 25 (This one’s easy, right?)

Explanation: As you see both the ending digits are 5 and also they both begin with 2. So we have satisfied both the conditions. Now how do we get 625? The first step is that you write down 25 on the right hand side. Why do we do so? Do not think about that right now. Just write 25 on the right hand side. Then we take the number on the left hand side (of 25), in this case 2. And we multiply it with its successor in the number line i.e. 3. Therefore we get the answer 2 x 3 = 6, which we write down on the right hand side. So we finally get the answer as 625.

Slight Modification to the Number 5 method ,

Rule: The ending number should add up to 10. Infact in the above case too the ending number 5 + 5 added upto 10. And the left hand side number should be same. This is very similar, so lets look at some example. 23 x 27 = 6 | 21 (I am sure that,not everyone finds this simple).

Explanation: Ending numbers 3 + 7 add upto 10. So the first rule is satisfied. And both the number on left hand side are same i.e. 2. First thing you do is, you multiply 3 x 7 = 21. And then like earlier you multiply 2 with the next higher digit number i.e. 3. And we get 2 x 3 = 6 on the left hand side. Final answer is 621.