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Learn to multiply any number by 11 rapidly. Using this Math trick you can multiply two digit numbers in your head faster than a calculator. The first trick will teach you how to multiply two digit numbers by 11, and the second trick will show you how to multiply three or more digit numbers by 11. This trick does not work for decimals.
Step 1. The first digit of the answer is the first digit being multiplied, which equals 4.
Step 2. The last digit of the answer will be the last number being multiplied,
which equals 3
Step 3. The middle term will be the sum of the two digits added together.
4 + 3 = 7
Final Answer =43 x 11 = 473
If the two terms added together for the middle term is greater then nine, then move a one to the left.
5 is the first term, 8 is the last, and add 5 + 8 = 13
13 is greater than 9 so move a 1 to the left.
Final answer = 638
To sum this trick up, add the digits and place the answer in between.
45 x 11 4+5 =9, place in between 4 and 5, final answer 495
78 X 11 = 7+8 =15 ( move a 1 to the left) final answer 858