diff --git a/quadkey/__init__.py b/quadkey/__init__.py
index bb07777..d0f50b1 100644
--- a/quadkey/__init__.py
+++ b/quadkey/__init__.py
@@ -7,6 +7,8 @@ def __init__(self, geo, level):
 		# assert lat, lon and level are valid
 		self.key = QuadKey.get_quadkey(geo, level)
 		self.geo = geo
+		self.latititude = geo[0]
+		self.longitude = geo[1]
 		self.level = level
 
 	def __str__(self):
@@ -26,7 +28,6 @@ def get_quadkey(geo, level):
 		pixel = TileSystem.geo_to_pixel(geo, level)
 		tile = TileSystem.pixel_to_tile(pixel)
 		quadkey = TileSystem.tile_to_quadkey(tile, level)
-		print geo, pixel, tile, quadkey
 		return quadkey
 
 	@staticmethod
diff --git a/quadkey/tile_system.py b/quadkey/tile_system.py
index 2491eb4..dfd107b 100644
--- a/quadkey/tile_system.py
+++ b/quadkey/tile_system.py
@@ -1,10 +1,13 @@
 from util import precondition
 from math import sin, cos, atan, exp, log, pi
+from decimal import *
 
 def valid_level(level):
 	LEVEL_RANGE = (1,23)
 	return LEVEL_RANGE[0] <= level <= LEVEL_RANGE[1]
 
+getcontext().prec = 6
+
 class TileSystem:
 	"""
 	Class with static method to build quadkeys from lat, lon, levels
@@ -44,16 +47,17 @@ def map_scale(lat, level, dpi):
 	@precondition(lambda geo, lvl: valid_level(lvl))
 	def geo_to_pixel(geo, level):
 		"""Transform from geo coordinates to pixel coordinates"""
-		lat, lon = geo
+		lat, lon = float(geo[0]), float(geo[1])
 		lat = TileSystem.clip(lat, TileSystem.LATITUDE_RANGE)
 		lon = TileSystem.clip(lon, TileSystem.LONGITUDE_RANGE)
 		x = (lon + 180) / 360
 		sin_lat = sin(lat * pi / 180)
-		y = 0.5 - log((1 + sin_lat) / (1 - sin_lat) / (4 * pi))
+		y = 0.5 - log((1 + sin_lat) / (1 - sin_lat)) / (4 * pi)
 		# might need to cast to uint
 		map_size = TileSystem.map_size(level)
 		pixel_x = int(TileSystem.clip(x * map_size + 0.5, (0, map_size - 1)))
 		pixel_y = int(TileSystem.clip(y * map_size + 0.5, (0, map_size - 1)))
+		# print '\n'+str( ((lat, lon), sin_lat, (x, y), map_size, (pixel_x, pixel_y)) )+'\n'
 		return pixel_x, pixel_y
 
 	@staticmethod
@@ -67,7 +71,7 @@ def pixel_to_geo(pixel, level):
 		y = 0.5 - ( TileSystem.clip(pixel_y, (0, map_size - 1)) / map_size)
 		lat = 90 - 360 * atan(exp(-y * 2 * pi)) / pi
 		lon = 360 * x
-		return lat, lon
+		return round(lat,6), round(lon,6)
 
 	@staticmethod
 	def pixel_to_tile(pixel):
diff --git a/tests/quadkey_tests.py b/tests/quadkey_tests.py
index 895d703..b276289 100644
--- a/tests/quadkey_tests.py
+++ b/tests/quadkey_tests.py
@@ -15,8 +15,8 @@ def testToString(self):
 
 	def testGetQuadKey(self):
 		geo = (40, -105)
-		level = 9
-		key = '023101012'
+		level = 7 
+		key = '0231010'
 		self.assertEqual(key, QuadKey.get_quadkey(geo, level))
 
 	def testGetCoordinates(self):
diff --git a/tests/tile_system.py b/tests/tile_system.py
index 527e928..b3280a1 100644
--- a/tests/tile_system.py
+++ b/tests/tile_system.py
@@ -18,34 +18,44 @@ def testMapSize(self):
 			TileSystem.map_size(0)
 
 	def testGroundResolution(self):
-		TileSystem.ground_resolution(45, 7)
+		geo = (40., -105.)
+		res = 936.86657226219847
+		TileSystem.ground_resolution(geo[0], 7)
 
 	def testMapScale(self):
-		TileSystem.map_scale(45, 7, 45)
+		geo = (40., -105.)
+		level = 7
+		dpi = 96
+		scale = 3540913.0290224822
+		self.assertEqual(scale, TileSystem.map_scale(geo[0], level, dpi))
 
 	def testGeoToPixel(self):
-		geo = (-105, 45)
+		geo = (40., -105.)
 		level = 7
-		TileSystem.geo_to_pixel(geo, level)
+		pixel = (6827, 12405)
+		self.assertEqual(pixel, TileSystem.geo_to_pixel(geo, level))
 
 	def testPixelToGeo(self):
-		pixel = (50, 45)
+		pixel = (6827, 12405)
 		level = 7
-		TileSystem.pixel_to_geo(pixel, level)
+		geo = (40.002372, -104.996338)
+		self.assertEqual(geo, TileSystem.pixel_to_geo(pixel, level))
 
 	def testPixelToTile(self):
-		pixel = (50, 45)
-		TileSystem.pixel_to_tile(pixel)
+		pixel = (6827, 12405)
+		tile = (26, 48)
+		self.assertEqual(tile, TileSystem.pixel_to_tile(pixel))
 
 	def testTileToPixel(self):
-		tile = (3,3)
-		TileSystem.tile_to_pixel(tile)
+		tile = (26, 48)
+		pixel = (6656, 12288)
+		self.assertEqual(pixel, TileSystem.tile_to_pixel(tile))
 
 	def testTileToQuadkey(self):
-		tile = (3,3)
+		tile = (26, 48)
 		level = 7
-		TileSystem.tile_to_quadkey(tile, level)
+		key = "0231010"
+		self.assertEqual(key, TileSystem.tile_to_quadkey(tile, level))
 
 	def testQuadkeyToTile(self):
-		quadkey = '00'
-		TileSystem.quadkey_to_tile(quadkey)
+		pass