if (A + mX)/(5 or 10)is divisible by m, then A is divisible by m. also if (A - mX)/(5 or 10)is divisible by m, then A is divisible by m.

eg. is 273 divisible by 7? ans; to obtain a number close to 273 that is divisible either by 5 or 10 , we can take X= 1 as m=7. then A+mX = 273+7*1=280 WHICH IS DIVISIBLE BY 10. THEREFORE 273 is divbisible by 7.

>if (A + mX)/(5 or 10)is divisible by m, then A is divisible >by m. >also if (A - mX)/(5 or 10)is divisible by m, then A is >divisible by m. > >eg. is 273 divisible by 7? >ans; to obtain a number close to 273 that is divisible >either by 5 or 10 , we can take X= 1 as m=7. then A+mX = >273+7*1=280 WHICH IS DIVISIBLE BY 10.

You probably meant to say that 280 is divisible by 7, right?