diff --git a/operator-prod.go b/operator-prod.go
index 5ef0cbc..950795a 100644
--- a/operator-prod.go
+++ b/operator-prod.go
@@ -34,16 +34,16 @@ func evalMultiply(ctx ExprContext, self *term) (v any, err error) {
 		s, _ := leftValue.(string)
 		n, _ := rightValue.(int64)
 		v = strings.Repeat(s, int(n))
-	} else if isNumber(leftValue) && isNumber(rightValue) {
+	} else if isNumOrFract(leftValue) && isNumOrFract(rightValue) {
 		if isFloat(leftValue) || isFloat(rightValue) {
 			v = numAsFloat(leftValue) * numAsFloat(rightValue)
+		} else if isFraction(leftValue) || isFraction(rightValue) {
+			v, err = mulAnyFract(leftValue, rightValue)
 		} else {
 			leftInt, _ := leftValue.(int64)
 			rightInt, _ := rightValue.(int64)
 			v = leftInt * rightInt
 		}
-	} else if isFraction(leftValue) || isFraction(rightValue) {
-		v, err = mulAnyFract(leftValue, rightValue)
 	} else {
 		err = self.errIncompatibleTypes(leftValue, rightValue)
 	}
@@ -71,7 +71,7 @@ func evalDivide(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	if isNumber(leftValue) && isNumber(rightValue) {
+	if isNumOrFract(leftValue) && isNumOrFract(rightValue) {
 		if isFloat(leftValue) || isFloat(rightValue) {
 			d := numAsFloat(rightValue)
 			if d == 0.0 {
@@ -79,6 +79,8 @@ func evalDivide(ctx ExprContext, self *term) (v any, err error) {
 			} else {
 				v = numAsFloat(leftValue) / d
 			}
+		} else if isFraction(leftValue) || isFraction(rightValue) {
+			v, err = divAnyFract(leftValue, rightValue)
 		} else {
 			leftInt, _ := leftValue.(int64)
 			if rightInt, _ := rightValue.(int64); rightInt == 0 {
@@ -87,8 +89,6 @@ func evalDivide(ctx ExprContext, self *term) (v any, err error) {
 				v = leftInt / rightInt
 			}
 		}
-	} else if isFraction(leftValue) || isFraction(rightValue) {
-		v, err = divAnyFract(leftValue, rightValue)
 	} else {
 		err = self.errIncompatibleTypes(leftValue, rightValue)
 	}
@@ -114,7 +114,7 @@ func evalDivideAsFloat(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	if isNumber(leftValue) && isNumber(rightValue) {
+	if isNumOrFract(leftValue) && isNumOrFract(rightValue) {
 		d := numAsFloat(rightValue)
 		if d == 0.0 {
 			err = errors.New("division by zero")
diff --git a/operator-sum.go b/operator-sum.go
index 352e5de..843a413 100644
--- a/operator-sum.go
+++ b/operator-sum.go
@@ -86,9 +86,11 @@ func evalMinus(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	if isNumber(leftValue) && isNumber(rightValue) {
+	if isNumOrFract(leftValue) && isNumOrFract(rightValue) {
 		if isFloat(leftValue) || isFloat(rightValue) {
 			v = numAsFloat(leftValue) - numAsFloat(rightValue)
+		} else if isFraction(leftValue) || isFraction(rightValue) {
+			v, err = subAnyFract(leftValue, rightValue)
 		} else {
 			leftInt, _ := leftValue.(int64)
 			rightInt, _ := rightValue.(int64)
@@ -104,8 +106,6 @@ func evalMinus(ctx ExprContext, self *term) (v any, err error) {
 			}
 		}
 		v = &diffList
-	} else if isFraction(leftValue) || isFraction(rightValue) {
-		v, err = subAnyFract(leftValue, rightValue)
 	} else {
 		err = self.errIncompatibleTypes(leftValue, rightValue)
 	}