Shortcut to square any number from 20 to 29 is an easy way to mentally square any number from 20 to 29. Knowing this trick can of great help especially when squaring a number forms part of a bigger question.
Below are the steps to find square of any number from 20 to 29 in seconds.
Step 1:First add the given number and the unit’s digit.
Step 2:Double the result obtained in step 1.
Step 3:Square the unit’s digit of the number given in question and place it next to the result obtained in step 2.
Examples
Example 1:Find the square of 22 in 5 seconds
22²=?
Step 1:Here the unit’s place digit is 2. Adding unit digit to the given number
we get,22 + 2=24
Step 2:Doubling the result in step1
we get, 24×2=48_
Step 3:Squaring the unit’ place digit
we get,22=4
Now put the result obtained in step 3 in step 2,we get
22²=484
Ans:484
Example 2:Find the square of 28 in 5 seconds.
28²=?
Step 1:Here the unit’s place digit is 8. Adding unit digit to the given number
we get,28+8=36
Step 2: Doubling the result in step1
we get, 36×2=72_
Step 3:Squaring the unit’ place digit
we get, 82= 64
Put the result obtained in step 2,Now carry forward ten’s place digit(6) to step 2 .
Step 4: Add carry forward from step 3 to result obtained in step 2
we get, 72+6=78
Put the unit’s place digit(4) the derived from step 3 next to result obtained in step 4.
we get, 784
28²=784
Ans:784
Example 3:Find the square of 23 in 5 seconds
23²=?
Step 1:Here the unit’s place digit is 3. Adding unit digit to the given number
we get,23 +3=26
Step 2:Doubling the result in step1
we get, 26×2=52_
Step 3:Squaring the unit’ place digit
we get,32=9
Now put the result obtained in step 3 in step 2,we get
23²=529
Ans:529