diff --git a/src/1_complex_numbers.md b/src/1_complex_numbers.md
index 9974490d23e232a43b6c15a242986d6cb377e1fc..994b0681d99a079a210e65e5177b5b04fdff35ea 100644
--- a/src/1_complex_numbers.md
+++ b/src/1_complex_numbers.md
@@ -116,7 +116,7 @@ involving cosines and sines.
 It also makes doing many common operations on complex number a lot easier.
 
 The exponential function $f(z) = \exp(z) = e^z$ is defined as:
-$$\exp(z) = e^{x + {\rm i}y} = e^{x} + e^{{\rm i} y} = e^{x} \left( \cos y + {\rm i} \sin y\right).$$
+$$\exp(z) = e^{x + {\rm i}y} = e^{x} e^{{\rm i} y} = e^{x} \left( \cos y + {\rm i} \sin y\right).$$
 The last expression is called the *Euler identity*.
 
 **Exercise** Check that this function obeys