diff --git a/Foundations/overview/calc.py b/Foundations/overview/calc.py
index 6cf5c54..11e534e 100644
--- a/Foundations/overview/calc.py
+++ b/Foundations/overview/calc.py
@@ -2,8 +2,8 @@ import math
 from decimal import *
 
 sec = 1000000
-min = 60 * sec
-hour = 60 * min
+minute = 60 * sec
+hour = 60 * minute
 day = 24 * hour
 month = 30 * day
 year = 365 * day
@@ -15,39 +15,41 @@ century = 100 * year
 # ==> n == exp(W(c))
 # see http://en.wikipedia.org/wiki/Lambert_W_function#Example_2
 
-def nlgn(c):
-	lower = 0.0
-	upper = 10e13
-	while True:
-		middle = (lower + upper) / 2
-		if lower == middle or middle == upper:
-			return middle
-		if middle * math.log(middle, 2) > c:
-			upper = middle
-		else:
-			lower = middle
+
+def n_lgn(c):
+    lower = 0.0
+    upper = 10e13
+    while True:
+        middle = (lower + upper) / 2
+        if lower == middle or middle == upper:
+            return middle
+        if middle * math.log(middle, 2) > c:
+            upper = middle
+        else:
+            lower = middle
+
 
 # n!
-def defactorial(c):
-	n = 0
-	while True:
-		if math.factorial(n) >= c:
-			return n - 1;
-		else:
-			n += 1
+def de_factorial(c):
+    n = 0
+    while True:
+        if math.factorial(n) >= c:
+            return n - 1
+        else:
+            n += 1
 
 # lg(n)
 print("2 ^ 10 ^ 6")
-print("2 ^ ( %d * 10 ^ 6 )" % (min/sec))
-print("2 ^ ( %d * 10 ^ 6 )" % (hour/sec))
-print("2 ^ ( %d * 10 ^ 6 )" % (day/sec))
-print("2 ^ ( %d * 10 ^ 6 )" % (month/sec))
-print("2 ^ ( %d * 10 ^ 6 )" % (year/sec))
-print("2 ^ ( %d * 10 ^ 6 )" % (century/sec))
+print("2 ^ ( %d * 10 ^ 6 )" % (minute / sec))
+print("2 ^ ( %d * 10 ^ 6 )" % (hour / sec))
+print("2 ^ ( %d * 10 ^ 6 )" % (day / sec))
+print("2 ^ ( %d * 10 ^ 6 )" % (month / sec))
+print("2 ^ ( %d * 10 ^ 6 )" % (year / sec))
+print("2 ^ ( %d * 10 ^ 6 )" % (century / sec))
 print("")
 # sqrt(n)
 print("{:.1e}".format(Decimal(sec ** 2)))
-print("{:.1e}".format(Decimal(min ** 2)))
+print("{:.1e}".format(Decimal(minute ** 2)))
 print("{:.3e}".format(Decimal(hour ** 2)))
 print("{:.5e}".format(Decimal(day ** 2)))
 print("{:.6e}".format(Decimal(month ** 2)))
@@ -56,7 +58,7 @@ print("{:.9e}".format(Decimal(century ** 2)))
 print("")
 # n
 print("{:.1e}".format(Decimal(sec)))
-print("{:.1e}".format(Decimal(min)))
+print("{:.1e}".format(Decimal(minute)))
 print("{:.1e}".format(Decimal(hour)))
 print("{:.2e}".format(Decimal(day)))
 print("{:.3e}".format(Decimal(month)))
@@ -64,17 +66,17 @@ print("{:.4e}".format(Decimal(year)))
 print("{:.4e}".format(Decimal(century)))
 print("")
 # n lg(n)
-print(nlgn(sec))
-print(nlgn(min))
-print(nlgn(hour))
-print(nlgn(day))
-print(nlgn(month))
-print(nlgn(year))
-print(nlgn(century))
+print(n_lgn(sec))
+print(n_lgn(minute))
+print(n_lgn(hour))
+print(n_lgn(day))
+print(n_lgn(month))
+print(n_lgn(year))
+print(n_lgn(century))
 print("")
 # n^2
 print(math.sqrt(sec))
-print(math.sqrt(min))
+print(math.sqrt(minute))
 print(math.sqrt(hour))
 print(math.sqrt(day))
 print(math.sqrt(month))
@@ -82,17 +84,17 @@ print(math.sqrt(year))
 print(math.sqrt(century))
 print("")
 # n^3
-print(sec ** (1/3.0))
-print(min ** (1/3.0))
-print(hour ** (1/3.0))
-print(day ** (1/3.0))
-print(month ** (1/3.0))
-print(year ** (1/3.0))
-print(century ** (1/3.0))
+print(sec ** (1 / 3.0))
+print(minute ** (1 / 3.0))
+print(hour ** (1 / 3.0))
+print(day ** (1 / 3.0))
+print(month ** (1 / 3.0))
+print(year ** (1 / 3.0))
+print(century ** (1 / 3.0))
 print("")
 # 2^n
 print(math.log(sec, 2))
-print(math.log(min, 2))
+print(math.log(minute, 2))
 print(math.log(hour, 2))
 print(math.log(day, 2))
 print(math.log(month, 2))
@@ -100,10 +102,10 @@ print(math.log(year, 2))
 print(math.log(century, 2))
 print("")
 # n!
-print(defactorial(sec))
-print(defactorial(min))
-print(defactorial(hour))
-print(defactorial(day))
-print(defactorial(month))
-print(defactorial(year))
-print(defactorial(century))
+print(de_factorial(sec))
+print(de_factorial(minute))
+print(de_factorial(hour))
+print(de_factorial(day))
+print(de_factorial(month))
+print(de_factorial(year))
+print(de_factorial(century))
\ No newline at end of file