Generally i m not good in maths; i always got average marks for this subject. Anyway i used it when i feel sleepy..hehehe, its better than u drink a coffee!
The story began with The 11 Rule....To multiply any two digit number by 11:
For this example i will use 72.
Separate the two digits in you mind (7__2).
Notice the hole between them!
Add the 7 and the 2 together (7+2=9)
Put the resulting 9 in the hole 792. That's it! 11 x 72=792
The only thing tricky to remember is that if the result of the addition is greater than 9, you only put the "ones" digit in the hole and carry the "tens" digit from the addition. For example 11 x 99 =? .... separate the two digits in yoyr mind, but ths time hve 2 holes (9_ _ 9). Use same method 9 + 9 = 18 >>> (9 18 9). Ths is not the final answer. When the no. is bigger than 9, u must ad '1' to the begining no. and let the no. '8' remain at the middle. So it will look like ths...(9+1) '8' '9'.....'1089'. Therefor, 99 x 11 = 1089.
How to multiply any two numbers from 11 to 19 using ur mind; the paperless way & simple? Try this: Take 17 x 14 for an example. Always place the larger number from the first no. =17 and only take ONE largest no. from the second = 4. So it covers the 17 and the 4. Those covered numbers are all you need. First step is u add 17 + 4 = 21 Add a zero behind it (multiply by 10) to get 210. Second step is u multiply the largest no. from each no. = '7' x '4''. So the answer is '28'.
Last step, add 210 + 28 = 238. Bravoooo! Yahoooooo! Try it u self.
Practice it on paper first! I hve try ths & it took me a few minutes to use my mind after that. U can do better than me, insyaAllah.
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took a lot of hours for me to digest this thing...how come u can do it during sleepy time?
ReplyDeletemay be u r not really interested abt it. Anyway Dib good in maths kan?
ReplyDeletetak sume silibus...selalu boleh jwb soklan yg ada gambar rajah je....
ReplyDeletePercaya tak - add math dib dpt C5..dan dib cuma jwb soklan sukatan membulat jer...hahaha