Description:
Quick: What's 25 × 45? How about 742 × 300? Or 4821 ÷ 9?
Most of us, when faced with math problems like these, immediately reach for a calculator or a pen. But imagine if you could perform these and other seemingly difficult—but surprisingly easy—calculations right in your head. Seems like an impossible feat? It's not.
Welcome po sa inyo!
Lets all be thankful to the hard work of the authors...
For BS Engineering (Civil) or even BS Mathematics out there,, try to check my profile for sometime, 'coz I'm goin' to update my thread soon regarding in good references/reviewers. TY.