Today was Catherine´s birthday. She turned 24. Catherine is twice as old as Ryan was when Catherine was as old as Ryan now. How old is Ryan now?..................
Multiplication Tip 3
To square any number a, first find the nearest multiple of 10 and find out how much you would have to add or subtract (b) to get to that number. Then do the opposite function (addition or subtraction) to get two numbers that average out to a (i.e. a + b and a – b). Multiply those two numbers and add the square of b.
Examples:
52 * 52 = (54 x 50) + 2*2 = 2704
96*96 = (100 x 92) + 4*4 = 9216
The above methodology was derived from the below formula.
a*a – b*b = (a+b)(a-b)
a*a = (a+b)(a-b) + b*b
This method is pretty simple as multiplying any number by multiples of ten is very easy.
