This algorithm is useful for kids that are lazy enough to memorize the multiplication table of 9.
The algorithm works like this:
Suppose you want a product of n and 9, you can do
- n – 1
- 10 -n
- The answer is (n-1) as the first digit and (10 – n) as the second digit.
Example:
4 x 9 =36
First digit: 4 – 1 = 3
Second digit: 10 – 4 = 6
Note: This trick only works on multiplication of any single digit number with 9.
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perghhhh something new aku belajar hari ni ni. hehe
tak pasang shoutbox ke eh ?
Anak2 sy ada satu cara mudah waktu kita ‘tolak’ nombor kecil di atas dengan nombot ‘besar’ di bawah
contoh
42
- 19
Proses dia kalau angka di bawah lagi besar, tolak dari bawah = 9-2 = 7
otometik dia akan tulis =3
4 tinggal 3, jadi senang untuk tolak 1.
Bila guna mcm ni. dia tak perlu bayangkankan dalam otak angka belas2…contoh tadi 4 di potong jadi 3. 2 tambah 10 akan jadi 12. Dari 12 baru di tolak 9.
Tapi sistem ini hanya berhasil jika kita hafal formula ini
Kalau
1 perlu tulis 9
2 perlu tulis 8
3 perlu tulis 7
4 perlu tulis 6
5 tetap dgn 5
Kujie: Menarik juga teknik ini
atok saya ajar cara ni..
listkan no 0-9 (0 1 2 3 4 5 6 7 8 9)
pastu listkan skali lagi tapi diterbalikkan (9 8 7 6 5 4 3 2 1 0)
so dia jadi macam ni…
0 9
1 8
2 7
3 6
4 5
5 4
6 3
7 2
8 1
9 0
Adilas last blog post..Old Mates II
Adila: Nice. However, your technique and neither mine could solve a multiplication of 2 digits number and a nine.
Great tips!
apasal tak guna calculator jer? lagi senang..