we have number from 1 to 2014. If we underline the number that divide by 3 and 4, how many pattern of two underlines that next to each other as example?(1,2,3,4,5,6,7,8,9,10,...,2014).

From 1 to 1000, how many time we use "5"?

Let a(1)=916 , a(2)=935 , a(3)=713  , a(4)=845  , a(5)=274  , a(6)=914 ,a(7)=255 . Find formula a(n)= ? ,n=1,2,3,....

Let OA=OB=OC=R=3,AB=3√2 and BC=2√2 .Find AC?

solve the system of equations (10a+3b+4c+d+e=0,11b+2c+2d+3e+f=0,15c+4d+5e+4f+g=0,2a+b-3c+12d-3e+f+g=0,6a-5b+3c-d+17e+f=0,3a+2b-3c+4d+e-16f+2g=0,4a-6b+c+d+3e+19g=0)