Add examples with 'dc -f' and 'dc -e'

pages/common/dc.md

@@ -6,14 +6,19 @@
 
 `dc`
 
-- Calculate 4 times 5 [4 5 *], subtract 17 [17 -], and [p]rint the output :
+- Execute dc script in file:
+
+`dc -f {{file}}`
+
+- Calculate 4 times 5 [4 5 *], subtract 17 [17 -], and [p]rint the output (using echo):
 
 `echo "4 5 * 17 - p"| dc`
 
-- Set number of decimal places to 10 [k 7], calculate 5 divided by -3 [5 _3 /] and [p]rint:
+- Set number of decimal places to 10 [k 7], calculate 5 divided by -3 [5 _3 /] and [p]rint (using dc -e):
 
-`echo "7 k 5 _3 / p" | dc`
+`dc -e "7 k 5 _3 / p"`
 
 - To 100 decimal places [100 k], calculate the golden ratio, phi: sqrt(5) [5 v] plus 1 [1 +], divided by 2 [2 /], and [p]rint result:
 
-`echo "100 k 5 v 1 + 2 / p" | dc`
+`dc -e "100 k 5 v 1 + 2 / p"`
+