Many people are terrified of mathematics. This list may help to improve the general knowledge of mathematical methods and speed up mathematical calculations in your head. This knowledge will help you amaze your math teacher.
Trick #1. Multiplication by 11
We all know that when multiplied by 10 you simply add 0 to the end of the number. But did you know that there is a simple way to multiply two-digit number by 11? Here it is:
Take the original number and imagine a space between two characters (in this example, we use the number 52):
Now add the two numbers and write them down in the middle:
Your answer will be:
If adding the numbers in parentheses obtained a two-digit number, just remember the second number and add one to the first number:
1089 – it always works!
Trick #2. Fast Squaring
This technique helps you quickly square a number that ends in 5. Here is who it goes:
1 – Take the first digit.
2 – Add one to it.
3 – Multiply the result on the first digit by the two digit number.
4 – At the end append 25. That’s it!
252 = ((2+1) x 2) place the first two “25”
2 x 3 = 6
625 – there you go!
Trick #3. Multiplication by 5
Most people memorizes the multiplication table for 5 very easily, but when dealing with large numbers, it gets complicated. Or does it? This technique is incredibly simple.
Take any number, divide by 2 (in other words, divide in half).
If the result is a whole number, assign 0 at the end. If not, do not pay attention to the value on the right side of the decimal point at the end and add 5. It always works:
2682 x 5 = (2682 / 2) & 5 or 0
2682 / 2 = 1341 (integer, so add 0)
Let’s try on another example:
5887 x 5
2943,5 (fractional number, skip the value on the right side of the decimal point, add 5)
Trick #4. Multiplication by 4
This is a very simple technique, although evident only for some. The trick is that you just need to multiply by 2, and then multiply by 2 again:
58 x 4 = (58 x 2) + (58 x 2) = (116) + (116) = 232
Trick #5. Complex Multiplications
If you need to multiply large numbers, and one of them – even, you can just rearrange them to get the answer:
32 x 125 is the same as:
16 x 250 is the same as:
8 x 500 ais the same as:
4 x 1000 = 4,000