diff --git a/exact-numbers/src/main/kotlin/xyz/lbres/exactnumbers/expressions/expression/Expression.kt b/exact-numbers/src/main/kotlin/xyz/lbres/exactnumbers/expressions/expression/Expression.kt
index 1d2e3cc..419f1dc 100644
--- a/exact-numbers/src/main/kotlin/xyz/lbres/exactnumbers/expressions/expression/Expression.kt
+++ b/exact-numbers/src/main/kotlin/xyz/lbres/exactnumbers/expressions/expression/Expression.kt
@@ -1,5 +1,7 @@
 package xyz.lbres.exactnumbers.expressions.expression
 
+import xyz.lbres.exactnumbers.expressions.term.Term
+
 abstract class Expression : Number() {
     abstract operator fun unaryMinus(): Expression
     abstract operator fun unaryPlus(): Expression
@@ -17,4 +19,9 @@ abstract class Expression : Number() {
     override fun toLong(): Long = 0 // TODO
     override fun toFloat(): Float = 0f // TODO
     override fun toDouble(): Double = 0.0 // TODO
+
+    companion object {
+        val ZERO: Expression = SimpleExpression(Term.ZERO)
+        val ONE: Expression = SimpleExpression(Term.ONE)
+    }
 }
diff --git a/exact-numbers/src/test/kotlin/xyz/lbres/exactnumbers/expressions/expression/SimpleExpressionTest.kt b/exact-numbers/src/test/kotlin/xyz/lbres/exactnumbers/expressions/expression/SimpleExpressionTest.kt
index bccddb4..0638fe5 100644
--- a/exact-numbers/src/test/kotlin/xyz/lbres/exactnumbers/expressions/expression/SimpleExpressionTest.kt
+++ b/exact-numbers/src/test/kotlin/xyz/lbres/exactnumbers/expressions/expression/SimpleExpressionTest.kt
@@ -1,25 +1,171 @@
 package xyz.lbres.exactnumbers.expressions.expression
 
+import xyz.lbres.exactnumbers.exactfraction.ExactFraction
+import xyz.lbres.exactnumbers.expressions.term.Term
+import xyz.lbres.exactnumbers.irrationals.log.Log
+import xyz.lbres.exactnumbers.irrationals.sqrt.Sqrt
+import xyz.lbres.exactnumbers.testutils.assertDivByZero
 import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNotEquals
 
 class SimpleExpressionTest {
     @Test
-    fun testConstructor() {
-        // TODO
+    fun testEquals() {
+        // equal
+        var term1 = Term.ONE
+        assertEquals(SimpleExpression(term1), SimpleExpression(term1))
+
+        term1 = Term.fromValues(ExactFraction(9, 13), emptyList())
+        assertEquals(SimpleExpression(term1), SimpleExpression(term1))
+
+        term1 = Term.fromValues(one, listOf(pi, piInverse, pi, testNumber1, log2, log4))
+        assertEquals(SimpleExpression(term1), SimpleExpression(term1))
+
+        term1 = Term.fromValues(one, listOf(pi, piInverse, pi))
+        var term2 = Term.fromValues(one, listOf(pi))
+        assertEquals(SimpleExpression(term1), SimpleExpression(term2))
+        assertEquals(SimpleExpression(term2), SimpleExpression(term1))
+
+        term1 = Term.fromValues(ExactFraction(-4, 7), listOf(Log.ZERO, Sqrt.ONE))
+        term2 = Term.ZERO
+        assertEquals(SimpleExpression(term1), SimpleExpression(term2))
+        assertEquals(SimpleExpression(term2), SimpleExpression(term1))
+
+        term1 = Term.fromValues(ExactFraction(-4, 7), listOf(testNumber2, Sqrt(ExactFraction(7, 9)), pi, log1, log1.inverse()))
+        term2 = Term.fromValues(ExactFraction(-4, 3), listOf(Sqrt(7), pi))
+        assertEquals(SimpleExpression(term1), SimpleExpression(term2))
+        assertEquals(SimpleExpression(term2), SimpleExpression(term1))
+
+        term1 = Term.fromValues(ExactFraction(-4, 7), listOf(testNumber2, Sqrt(ExactFraction(7, 9)), pi, log1, log1.inverse()))
+        term2 = Term.fromValues(ExactFraction(-4, 3), listOf(Sqrt(7), Sqrt.ONE, piInverse, pi, pi))
+        assertEquals(SimpleExpression(term1), SimpleExpression(term2))
+        assertEquals(SimpleExpression(term2), SimpleExpression(term1))
+
+        // not equal
+        term1 = Term.ONE
+        term2 = -Term.ONE
+        assertNotEquals(SimpleExpression(term1), SimpleExpression(term2))
+        assertNotEquals(SimpleExpression(term2), SimpleExpression(term1))
+
+        term1 = Term.fromValues(ExactFraction.TWO, emptyList())
+        term2 = Term.fromValues(ExactFraction.HALF, emptyList())
+        assertNotEquals(SimpleExpression(term1), SimpleExpression(term2))
+        assertNotEquals(SimpleExpression(term2), SimpleExpression(term1))
+
+        term1 = Term.fromValues(one, listOf(pi))
+        term2 = Term.fromValues(one, listOf(piInverse))
+        assertNotEquals(SimpleExpression(term1), SimpleExpression(term2))
+        assertNotEquals(SimpleExpression(term2), SimpleExpression(term1))
+
+        term1 = Term.fromValues(ExactFraction(-4, 7), listOf(testNumber2, Sqrt(ExactFraction(7, 9)), pi, log1, log1.inverse()))
+        term2 = Term.fromValues(ExactFraction(-4, 3), listOf(Sqrt(7), Sqrt.ONE, piInverse, pi))
+        assertNotEquals(SimpleExpression(term1), SimpleExpression(term2))
+        assertNotEquals(SimpleExpression(term2), SimpleExpression(term1))
     }
 
     @Test
     fun testUnaryMinus() {
-        // TODO
+        var expr = SimpleExpression(Term.ZERO)
+        var expected = SimpleExpression(Term.ZERO)
+        assertEquals(expected, -expr)
+
+        expr = SimpleExpression(Term.fromValues(one, listOf(Log.ONE)))
+        expected = SimpleExpression(Term.fromValues(-one, listOf(Log.ONE)))
+        assertEquals(expected, -expr)
+
+        expr = SimpleExpression(Term.fromValues(one, listOf(pi)))
+        expected = SimpleExpression(Term.fromValues(-one, listOf(pi)))
+        assertEquals(expected, -expr)
+
+        expr = SimpleExpression(Term.fromValues(ExactFraction(44, 15), emptyList()))
+        expected = SimpleExpression(Term.fromValues(ExactFraction(-44, 15), emptyList()))
+        assertEquals(expected, -expr)
+
+        expr = SimpleExpression(
+            Term.fromValues(
+                ExactFraction(-15, 44),
+                listOf(log2, log3, log4, Sqrt(ExactFraction(64, 9)), pi, piInverse)
+            )
+        )
+        expected = SimpleExpression(
+            Term.fromValues(
+                ExactFraction(15, 44),
+                listOf(log2, log3, log4, Sqrt(ExactFraction(64, 9)), pi, piInverse)
+            )
+        )
+        assertEquals(expected, -expr)
     }
 
     @Test
     fun testUnaryPlus() {
-        // TODO
+        var expr = SimpleExpression(Term.ZERO)
+        assertEquals(expr, +expr)
+
+        expr = SimpleExpression(Term.fromValues(one, listOf(Log.ONE)))
+        assertEquals(expr, +expr)
+
+        expr = SimpleExpression(Term.fromValues(one, listOf(pi)))
+        assertEquals(expr, +expr)
+
+        expr = SimpleExpression(Term.fromValues(ExactFraction(44, 15), emptyList()))
+        assertEquals(expr, +expr)
+
+        expr = SimpleExpression(
+            Term.fromValues(
+                ExactFraction(-15, 44),
+                listOf(log2, log3, log4, Sqrt(ExactFraction(64, 9)), pi, piInverse)
+            )
+        )
+        assertEquals(expr, +expr)
     }
 
     @Test
     fun testInverse() {
-        // TODO
+        assertDivByZero { SimpleExpression(Term.ZERO).inverse() }
+
+        var expr1 = SimpleExpression(Term.ONE)
+        var expr2 = SimpleExpression(Term.ONE)
+        assertEquals(expr1, expr2.inverse())
+
+        expr1 = SimpleExpression(Term.fromValues(ExactFraction(17, 12), emptyList()))
+        expr2 = SimpleExpression(Term.fromValues(ExactFraction(12, 17), emptyList()))
+        assertEquals(expr1, expr2.inverse())
+        assertEquals(expr2, expr1.inverse())
+
+        expr1 = SimpleExpression(Term.fromValues(one, listOf(log3)))
+        expr2 = SimpleExpression(Term.fromValues(one, listOf(log3.inverse())))
+        assertEquals(expr1, expr2.inverse())
+        assertEquals(expr2, expr1.inverse())
+
+        expr1 = SimpleExpression(Term.fromValues(one, listOf(pi, piInverse, sqrt2)))
+        expr2 = SimpleExpression(Term.fromValues(one, listOf(pi, piInverse, sqrt2.inverse())))
+        assertEquals(expr1, expr2.inverse())
+        assertEquals(expr2, expr1.inverse())
+
+        expr1 = SimpleExpression(Term.fromValues(ExactFraction(-1, 9), listOf(testNumber2, testNumber2, pi, log4, pi, sqrt1)))
+        expr2 = SimpleExpression(
+            Term.fromValues(
+                -ExactFraction.NINE,
+                listOf(testNumber2.inverse(), testNumber2.inverse(), piInverse, piInverse, log4.inverse(), sqrt1.inverse())
+            )
+        )
+        assertEquals(expr1, expr2.inverse())
+        assertEquals(expr2, expr1.inverse())
+
+        expr1 = SimpleExpression(
+            Term.fromValues(
+                ExactFraction(100, 99999999999),
+                listOf(Log(4), pi, pi, Log(14, 3))
+            )
+        )
+        expr2 = SimpleExpression(
+            Term.fromValues(
+                ExactFraction(99999999999, 100),
+                listOf(Log(4).inverse(), piInverse, piInverse, Log(14, 3).inverse())
+            )
+        )
+        assertEquals(expr1, expr2.inverse())
+        assertEquals(expr2, expr1.inverse())
     }
 }
diff --git a/exact-numbers/src/test/kotlin/xyz/lbres/exactnumbers/expressions/expression/testutils.kt b/exact-numbers/src/test/kotlin/xyz/lbres/exactnumbers/expressions/expression/testutils.kt
new file mode 100644
index 0000000..859c7f9
--- /dev/null
+++ b/exact-numbers/src/test/kotlin/xyz/lbres/exactnumbers/expressions/expression/testutils.kt
@@ -0,0 +1,21 @@
+package xyz.lbres.exactnumbers.expressions.expression
+
+import xyz.lbres.exactnumbers.exactfraction.ExactFraction
+import xyz.lbres.exactnumbers.irrationals.log.Log
+import xyz.lbres.exactnumbers.irrationals.pi.Pi
+import xyz.lbres.exactnumbers.irrationals.sqrt.Sqrt
+import xyz.lbres.exactnumbers.testutils.TestNumber
+
+// constants to use in tests
+val log1 = Log(ExactFraction(15, 4))
+val log2 = Log(8, 7)
+val log3 = Log(ExactFraction(19, 33)).inverse()
+val log4 = Log(ExactFraction(25, 121))
+val sqrt1 = Sqrt(99)
+val sqrt2 = Sqrt(ExactFraction(64, 121))
+val sqrt3 = Sqrt(ExactFraction(15, 44))
+val pi = Pi()
+val piInverse = Pi().inverse()
+val testNumber1 = TestNumber(ExactFraction(3, 4))
+val testNumber2 = TestNumber(ExactFraction.SEVEN)
+val one = ExactFraction.ONE