Secondly, for the first time in many students' math career, they see WHY something works, not just HOW. This is a huge step in their Math "thinking". They are no longer "innumerate". Quick, give me an estimate of the are of a circle with radius 47 cm: no calculator allowed. The art of Mental Math is being lost with the calculator generation. Also this is a wonderful example of how we can apply the (a + b)^2 formula.

i've heard this one before, but now I know why it works :) thanks

Great. This helped A LOT!

Nice video.

nice!

sweet

Okay guys, enough. Arguments should be won by logic, not who yells the loudest or who swears the most. I use mental arithmetic daily because I see mathematics around me all the time. Others don't, so this will not be as important to them. It's a personal thing. However, it is a cool use for squaring a binomial.

coool.

i can tell you some more tricks but they're a bit harde(but i think u already know them)... cus multiplting by 5 is easy..let's take a number 67 for example. you add 7 to that cus it's the last digit-you'll get 74.you'll now multiply it by 6 cus the number began with 6 , 74*6=444. now you'll multiply that with10.get4440and add 6^2=36 to end and you'll get 4476.same trick works for every number.I figured it out by myself but they're probably figured out by someone else aswell.anyways

Omg thats so cheeky!

I can see that we are going to have to agree to disagree on this subject. I use mental math all the time, answers, or estimates, within seconds. I was just at a client's office, we uploaded 602 records and quickly checked about 40 of them. They all were perfect. Does that mean all 602 were perfectly uploaded? No, but how sure are you? Through mental arithmetic I was able to get an answer. I see and use this EVERY day. Sure, I use a calculator, but only 75% of the time, my students do.

We're all going to be laughing when you're the one loosing money because you didn't know how to punch the numbers in your calculator correctly.

Wow, you just don't get it do you. If you arm yourself with ten or so quick Math tricks, then you are not reaching for a calculator every time you have to do some arithmetic. Believe me I have seen students go into their back pack, get out their calculator and get the answer on their calculator when they are asked to do 51^2, or 53 x 11 and so on. So who is wasting their time here. See next comment too.