Let me just start by saying I'm horrible at math... but I'd like to get better at quickly adding numbers in my head.
I'm not sure if this is the right place to ask, but I was wondering if any of you guys have suggestions or strategies on how to quickly add numbers <100 in your head.
If you know of any books that will help me out with this simple task, just let me know, but I would like to learn how you guys go about doing it, thanks!
ok, I don't know any big trick for adding numbers under 100 but there are some easy to know shortcuts :
1) always go with the the multiples of ten : add them up.
2) Add the numbers in the units together.
3) Add 1) with 2)
ex.: 43 + 27 :
1) 40 + 20 = 60
2) 3 + 7 =10
3) 60 + 10 = 70
It seems long but if you get used to this it will be, I think, very fast because it is easier than adding directly 43 + 27
Another thing you can look foris whether the units form ten or are very near to it.
17 + 62
17 + 63 would be easy to calculate. That gives 80. Well we had one too much, which we are going to remove again.
So 17+62 =79.
I agree with hemza, add from left to right. The way to become a human calculator is to get the math to the same part of the brain that controls language. That is the fastest part of the brain. If you use this part of the brain, you will just see the answer.