To find the sum (displayed using 7 digits) of the series
use
a := 'sum( sin(n)/(1+3*n^2), n=5..69 )'; evalf(a,7);The first statement assigns a the sum of the series. The second obtains a 7 digit numerical value for a. The quotes in the definition of a tell Maple NOT to evaluate a right away. Repeat the above commands omitting the quotes in the definition of a - see what happens.