Compute
1/(1 * 4) + 1/(4 * 7) + 1/(7 * 10)
1/(1*4)+1/(4*7)+1/(7*10)
= 1/4+1/28+1/70
Using the common denominator of 140:
35/140+5/140+2/140
= 42/140
= 3/10
3/10 or 0.3
