CROSS MULTIPLICATION

Start from r.h.s, if there is any carry in any part,it is to be added to next part. A B C D C*A (D.A + B*C) B*D

*4 1*3+4*2 2*

*5 1*6+5*4 6*

MULTIPLICATION OF NUMBERS WHERE DIFFRENCE IS even :

We know : (a+1) * (a-1) = a * a – 1 24 * 26 Find the midpoint of 24 and 26 i.e. 25 Now square of 25 = 625 Final answer = = 624 =24*26

49 * * 50 = = *86 85*85=8*9 25= =7224

We know (a-2)*(a+2) = a*a – 4 21 * 25 Find the Mid point of 21 and 25 i.e. 23 Now square of mid point : 23*23 = 529 Final answer = 529 – 4 = 525

47 * 43 Mid point – 45 45*45=4*5|5*5= = *84 Mid point – * 86 = = 7392