How to Quickly Square any 2-digit Number Mentally
The above video by Mathemagician Art Benjamin shows an ingenious way of squaring any 2-digit numbers easily without a calculator. If you practice and master this technique, it serves as an amusing and fanciful trick to "show off" to you friends! Besides, it is also a good way to train your mental arithmetic skills.
Some examples that depicts his technique:
Pre-requisite to the trick:
You have to be proficient in multiplying a 2 digit by 1 digit number mentally.
Mathematics Behind it:
The math behind the technique is based on the "difference of 2 squares" identity that we learn in our secondary 2 math syllabus in Singapore.
Practice!
Practice LOTS to become really good at it!
Try squaring the following numbers and check with a calculator!
a) 41
b) 29
c) 37
d) 42
e) 38
f) 53
g) 69
h) 76
i) 67
j) 88
k) 94
l) 55
m) 73
n) 75
o) 19
Keep practicing and master this technique of squaring any 2-digit number quickly using mental arithmetic!
To get professional help (Math tuition) on secondary school mathematics in Singapore, click here.
Mr Ausome
