Now, Squaring A Number Between 40 – 49 Mentally

 

40 - 49

 

In my previous post, we have learnt how to mentally square a number in the range 50-59.  Today, we are going to learn how to square a number in the range 40-49, mentally.

Let say we want to find 48².  Here are the steps :

Step 1 : Find the difference between 48 and 50 :

50 – 48 = 2.

Step 2 : Square that 2 :

2² = 4.

So write mentally 04 (2 place values answer)

Step 3 : Subtract the result of step 1 from 25 :

25 – 2 = 23

Step 4 : Attach the results of step 3 and step 2 :

Therefore 48² = 2304

Ok, another examples :

Example 1 : Find 47².

(a)  50 – 57 = 3

(b)  3² = 9.  Remember it as 09

(c)  25 – 3 = 22

(d)  Therefore, 47² = 2209

Example 2 : Find 41².

(a)  50 – 41 = 9

(b) 9² = 81.  Remember this.

(c)  25 – 9 = 16

(d)  Therefore, 41² = 1681 

It is simple, isn’t it?  So easy to work it out mentally🙂

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Posted on June 16, 2009, in Info Matematik. Bookmark the permalink. Leave a comment.

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