added a function to check if whole number (#14)

number/number.go

@@ -0,0 +1,10 @@
+package number
+
+import "math"
+
+func IsWhole(num float64) bool {
+	if math.IsInf(num, 0) || math.IsNaN(num) {
+		return false
+	}
+	return math.Trunc(num) == num
+}

number/number_test.go

@@ -0,0 +1,61 @@
+package number
+
+import (
+	"fmt"
+	"math"
+	"testing"
+)
+
+func TestIsWhole(t *testing.T) {
+	tests := []struct {
+		input    float64
+		expected bool
+	}{
+		{
+			input:    0.000,
+			expected: true,
+		},
+		{
+			input:    2.90,
+			expected: false,
+		},
+		{
+			input:    1.9,
+			expected: false,
+		},
+		{
+			input:    1,
+			expected: true,
+		},
+		{
+			input:    0.11,
+			expected: false,
+		},
+		{
+			input:    -0.11,
+			expected: false,
+		},
+		{
+			input:    -1,
+			expected: true,
+		},
+		{
+			input:    math.Inf(-1),
+			expected: false,
+		},
+		{
+			input:    math.Inf(1),
+			expected: false,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(fmt.Sprintf("test isWholeNumber for %f", test.input), func(t *testing.T) {
+			resp := IsWhole(test.input)
+
+			if resp != test.expected {
+				t.Errorf("unexpected result %v", resp)
+			}
+		})
+	}
+}