You know that 5 x 5 = 25. However, do you realize that the square of any number that ends with 5, will also contains 25 in the last 2 digits.
Example 1:
25 x 25 = 625
Steps:
Remove the last digit. We get 2.
1 + 2 = 3 <– Add 1.
3 x 2 = 6 <– Multiply 2 times the result.
6 and 25 give 625 <– Concatenate the result with 25.
Example 2:
205 x 205 = 42025
Steps:
Remove the last digit. We get 20.
1 + 20 = 21 <– Add 1.
21 x 20 = 420 <– Multiply 20 times the result.
420 and 25 give 42025 <– Concatenate the result with 25.
Example 3:
315 x 315 = 99225
Steps:
Remove the last digit. We get 31.
1 + 31 = 32 <– Add 1.
32 x 31 = 992<– Multiply 31 times the result.
992 and 25 give 99225 <– Concatenate the result with 25.
If you have better method to share, please don’t hesitate to leave your comment.
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patutla aku tak suka math… hahaha
Come on. Secondary school maths is not that hard.
macam mudah je..isshhh
Memang mudah. Boleh buat dalam kepala. Tidak perlu kertas dan pen. Jika nombor tu besar sangat, mungkin perlukan kertas dan pen. Persoalannya berapa besar itu besar. Jawapannya bergantung kepada kapasiti otak.