alt solution to exercise 4

Uses nbytes instead of itemsize * size

source/exercises100.ktx

@@ -37,6 +37,9 @@ hint: size, itemsize
 Z = np.zeros((10,10))
 print("%d bytes" % (Z.size * Z.itemsize))
 
+# Simpler alternative
+print("%d bytes" % Z.nbytes)
+
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 How to get the documentation of the numpy add function from the command line? (★☆☆)