Magical Math formula and tricks

1. INSTANT MULTIPLICATION

how to multiply, in your head, any two-digit number by eleven. It’s very easy once you know the secret. Consider the problem:

32 x 11

To solve this problem, simply add the digits, 3 + 2 = 5 , put the 5 between the 3 and the 2, and there is your answer:  352

 Suppose the problem is

85 x 11

Although 8 + 5 = 1 3 , the answer is NOT 81 3 5 ! As before, the 3 goes in between the numbers, but the 1 needs to be added to the 8 to get the 

correct answer: 93 5               or 1+835 =935

2. SQUARING AND MORE

That method is especially simple when the number ends in 5, so let’s do that trick now. 

To square a two-digit number that ends in 5, you need to remember only two things.

1. The answer begins by multiplying the first digit by the next higher digit.

 2. The answer ends in 25.

For example, to square the number 35, we simply multiply the first digit (3) by the next higher digit (4), then attach 25. Since 3x4 =12, the answer is 1225. Therefore, 35x35 =1225.

 Our steps can be illustrated this way:

35

 x 35

 3 x 4 = 12

 5 x 5 = 25  

Answer:1225

NOTE:-We can use a similar trick when multiplying two-digit numbers with the same first digit, and second digits that sum to 10.
For example, let’s try 83x87. (Both numbers begin with 8, and the last digits sum to 3 + 7 = 10.) Since      8 x 9 = 72, and 3 x 7 = 21, the answer is 7221.

83 x 87

 8 x 9 = 72 

3 x 7 = 21

 Answer:7221

Similarly, 84 x 86 = 7224.