diff --git a/cointop/portfolio.go b/cointop/portfolio.go
index 0317040..b01feb8 100644
--- a/cointop/portfolio.go
+++ b/cointop/portfolio.go
@@ -12,6 +12,7 @@ import (
 	"time"
 	"unicode/utf8"
 
+	"github.com/Knetic/govaluate"
 	"github.com/miguelmota/cointop/pkg/asciitable"
 	"github.com/miguelmota/cointop/pkg/humanize"
 	"github.com/miguelmota/cointop/pkg/pad"
@@ -434,16 +435,24 @@ func (ct *Cointop) SetPortfolioHoldings() error {
 		return nil
 	}
 
-	value := normalizeFloatString(string(b), true)
-	shouldDelete := value == ""
-	var holdings float64
-
-	if !shouldDelete {
-		holdings, err = strconv.ParseFloat(value, 64)
+	var holdings float64 = 0
+	input := strings.TrimSpace(string(b[:n])) // remove trailing \0s
+	if input != "" {
+		expression, err := govaluate.NewEvaluableExpression(input)
 		if err != nil {
-			return err
+			return nil // invalid expression - don't change anything
+		}
+		result, err := expression.Evaluate(nil)
+		if err != nil {
+			return nil // could not evaluate - don't change anything
+		}
+		var ok bool
+		holdings, ok = result.(float64)
+		if !ok {
+			return nil // not a float64 - don't change anything
 		}
 	}
+	shouldDelete := holdings == 0
 
 	idx := ct.GetPortfolioCoinIndex(coin)
 	if err := ct.SetPortfolioEntry(coin.Name, holdings); err != nil {
diff --git a/docs/content/faq.md b/docs/content/faq.md
index 0392af4..fd32e45 100644
--- a/docs/content/faq.md
+++ b/docs/content/faq.md
@@ -165,6 +165,8 @@ draft: false
 
   Press <kbd>e</kbd> on the highlighted coin to enter holdings and add to your portfolio.
 
+  This dialog supports basic expressions including `+` `-` `*` etc.
+
 ## How do I edit the holdings of a coin in my portfolio?
 
   Press <kbd>e</kbd> on the highlighted coin to edit the holdings.
diff --git a/go.mod b/go.mod
index 51f8410..9495c01 100644
--- a/go.mod
+++ b/go.mod
@@ -2,6 +2,7 @@ module github.com/miguelmota/cointop
 
 require (
 	github.com/BurntSushi/toml v0.3.1
+	github.com/Knetic/govaluate v3.0.0+incompatible // indirect
 	github.com/acarl005/stripansi v0.0.0-20180116102854-5a71ef0e047d
 	github.com/anaskhan96/soup v1.1.1 // indirect
 	github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be // indirect
diff --git a/go.sum b/go.sum
index c23e45c..30911b7 100644
--- a/go.sum
+++ b/go.sum
@@ -1,6 +1,8 @@
 cloud.google.com/go v0.26.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
 github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/Knetic/govaluate v3.0.0+incompatible h1:7o6+MAPhYTCF0+fdvoz1xDedhRb4f6s9Tn1Tt7/WTEg=
+github.com/Knetic/govaluate v3.0.0+incompatible/go.mod h1:r7JcOSlj0wfOMncg0iLm8Leh48TZaKVeNIfJntJ2wa0=
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
 github.com/acarl005/stripansi v0.0.0-20180116102854-5a71ef0e047d h1:licZJFw2RwpHMqeKTCYkitsPqHNxTmd4SNR5r94FGM8=
 github.com/acarl005/stripansi v0.0.0-20180116102854-5a71ef0e047d/go.mod h1:asat636LX7Bqt5lYEZ27JNDcqxfjdBQuJ/MM4CN/Lzo=