Archive for the ‘Mathematics’ Category

Test for divisibility by 7

Thursday, May 2nd, 2013

EXAMPLE  343

1 Take unit digit i.e. 3 in this case.

2 multiply it by 2 i.e. 3*2=6.

3 subtract it from first two digits i.e. 34-6=28.

4 as 28 is divisible by 7,343 would also be divisible by 7.

For 4 digit number 3592

359-4

355

35-10

25 not divisible by 7 so 3592 will not be divisible.

You can test it for 3591

 

Lattice Multiplication

Thursday, April 18th, 2013

https://www.khanacademy.org/math/arithmetic/multiplication-division/lattice_multiplication