Luffy the pirate's answer to A Philips's Secondary 3 E Maths Singapore question.
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Must able to find the middle number so you can add and subtract by the same amount.
Eg 90 x 88 = ( 89 + 1) ( 89- 1)
The middle number is 89.
The same amount is 1.
With that, you can use algebraic identities to solve. (a+b)(a-b) =(a^2 - b^2)
Hope that helps
Eg 90 x 88 = ( 89 + 1) ( 89- 1)
The middle number is 89.
The same amount is 1.
With that, you can use algebraic identities to solve. (a+b)(a-b) =(a^2 - b^2)
Hope that helps
Date Posted:
1 year ago
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