diff --git a/primes/matho-mult b/primes/matho-mult
index ff9d599..1242935 100755
--- a/primes/matho-mult
+++ b/primes/matho-mult
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#! /usr/bin/python3
 
 # Python program to multiply many large integers separated by spaces or newlines.
 # The integers to multiply may be entered on the command-line or into standard input.
@@ -15,7 +15,7 @@ if (args == []):
 	# read stdin if no command line args
 	while True:
 		try:
-			input_line = raw_input()
+			input_line = input()
 		except:
 			break;
 		for s in string.split(input_line):
@@ -24,4 +24,4 @@ else:
 	# multiply together the command-line args
 	for arg in args:
 		prod *= int(arg)
-print prod
+print(prod)
diff --git a/primes/matho-sum b/primes/matho-sum
index 34b5bbd..1f47401 100755
--- a/primes/matho-sum
+++ b/primes/matho-sum
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#! /usr/bin/python3
 
 # Python program to sum many large integers separated by spaces or newlines.
 # The integers to sum may be entered on the command-line or into standard input.
@@ -12,7 +12,7 @@ if (args == []):
 	# read stdin if no command line args
 	while True:
 		try:
-			input_line = raw_input()
+			input_line = input()
 		except:
 			break;
 		for s in string.split(input_line):
@@ -21,4 +21,4 @@ else:
 	# sum together the command-line args
 	for arg in args:
 		sum += int(arg)
-print sum
+print(sum)
diff --git a/primes/primorial b/primes/primorial
index e5c55fe..9e9923f 100755
--- a/primes/primorial
+++ b/primes/primorial
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#! /usr/bin/python3
 
 # This is a Python program to display large primorials.
 # A primorial is the product of all primes up to the given number.
@@ -16,11 +16,11 @@ import os
 import sys
 
 def usage(ev):
-	print "This program calculates large primorials."
-	print
-	print "Usage: %s integers" % os.path.basename(sys.argv[0])
-	print
-	print "A primorial is the product of all primes up to the given number."
+	print("This program calculates large primorials.")
+	print()
+	print("Usage: %s integers" % os.path.basename(sys.argv[0]))
+	print()
+	print("A primorial is the product of all primes up to the given number.")
 	sys.exit(ev)
 
 def output_primorial(arg):
@@ -36,9 +36,9 @@ else:
 	for arg in args:
 		try:
 			if (int(arg) < 1):
-				print >>sys.stderr, "Number too small."
+				print("Number too small.", file=sys.stderr)
 				sys.exit(1)
 		except:
-			print >>sys.stderr, "Positive integer required."
+			print("Positive integer required.", file=sys.stderr)
 			usage(1)
 		output_primorial(arg)