diff --git a/README.md b/README.md
index 1890104..5d7b91e 100644
--- a/README.md
+++ b/README.md
@@ -88,6 +88,14 @@ Hand: 1
 └─────────┴──────┴──────┴─────────┴─────────────┴───────────┴───────┘
 ```
 
+## use as a module
+
+```js
+const simulateHands = require('./hands.js')
+const result = simulateHands(1)
+console.log(result.sessionSummary)
+```
+
 ## table rules
 
 `playHand` accepts a `rules` object that controls minimum bets and odds limits.
diff --git a/hands.js b/hands.js
index 37db28d..e1e965b 100644
--- a/hands.js
+++ b/hands.js
@@ -1,158 +1,170 @@
+#!/usr/bin/env node
 'use strict'
 
 const { playHand } = require('./index.js')
 const { minPassLineMaxOddsPlaceSixEight } = require('./betting.js')
 
-const numHands = parseInt(process.argv.slice(2)[0], 10)
-const showDetail = process.argv.slice(2)[1]
-
-console.log(`Simulating ${numHands} Craps Hand(s)`)
-console.log('Using betting strategy: minPassLineMaxOddsPlaceSixEight')
-
-const summaryTemplate = {
-  balance: 0,
-  rollCount: 0,
-  pointsSet: 0,
-  pointsWon: 0,
-  comeOutWins: 0,
-  comeOutLosses: 0,
-  netComeOutWins: 0,
-  neutrals: 0,
-  placeSixWins: 0,
-  placeSixLosses: 0,
-  placeEightWins: 0,
-  placeEightLosses: 0,
-  dist: {
-    2: { ct: 0, prob: 1 / 36 },
-    3: { ct: 0, prob: 2 / 36 },
-    4: { ct: 0, prob: 3 / 36 },
-    5: { ct: 0, prob: 4 / 36 },
-    6: { ct: 0, prob: 5 / 36 },
-    7: { ct: 0, prob: 6 / 36 },
-    8: { ct: 0, prob: 5 / 36 },
-    9: { ct: 0, prob: 4 / 36 },
-    10: { ct: 0, prob: 3 / 36 },
-    11: { ct: 0, prob: 2 / 36 },
-    12: { ct: 0, prob: 1 / 36 }
-  }
-}
-
-const sessionSummary = Object.assign({}, summaryTemplate)
-
-const hands = []
-const rules = {
-  minBet: 10,
-  maxOddsMultiple: {
-    4: 3,
-    5: 4,
-    6: 5,
-    8: 5,
-    9: 4,
-    10: 3
+function simulateHands (numHands, showDetail) {
+  const summaryTemplate = {
+    balance: 0,
+    rollCount: 0,
+    pointsSet: 0,
+    pointsWon: 0,
+    comeOutWins: 0,
+    comeOutLosses: 0,
+    netComeOutWins: 0,
+    neutrals: 0,
+    placeSixWins: 0,
+    placeSixLosses: 0,
+    placeEightWins: 0,
+    placeEightLosses: 0,
+    dist: {
+      2: { ct: 0, prob: 1 / 36 },
+      3: { ct: 0, prob: 2 / 36 },
+      4: { ct: 0, prob: 3 / 36 },
+      5: { ct: 0, prob: 4 / 36 },
+      6: { ct: 0, prob: 5 / 36 },
+      7: { ct: 0, prob: 6 / 36 },
+      8: { ct: 0, prob: 5 / 36 },
+      9: { ct: 0, prob: 4 / 36 },
+      10: { ct: 0, prob: 3 / 36 },
+      11: { ct: 0, prob: 2 / 36 },
+      12: { ct: 0, prob: 1 / 36 }
+    }
   }
-}
-
-console.log(`[table rules] minimum bet: $${rules.minBet}`)
 
-for (let i = 0; i < numHands; i++) {
-  if (process.env.DEBUG) {
-    console.log(`\n================ HAND ${i + 1} ================`)
-  }
-  const hand = playHand({ rules, bettingStrategy: minPassLineMaxOddsPlaceSixEight })
-  hand.summary = Object.assign({}, summaryTemplate)
-
-  sessionSummary.balance += hand.balance
-  hand.summary.balance = hand.balance
-
-  hand.history.reduce((memo, roll) => {
-    memo.rollCount++
-    hand.summary.rollCount++
-    memo.dist[roll.diceSum].ct++
-
-    switch (roll.result) {
-      case 'neutral':
-        memo.neutrals++
-        hand.summary.neutrals++
-        break
-      case 'point set':
-        memo.pointsSet++
-        hand.summary.pointsSet++
-        break
-      case 'point win':
-        memo.pointsWon++
-        hand.summary.pointsWon++
-        break
-      case 'comeout win':
-        memo.comeOutWins++
-        hand.summary.comeOutWins++
-        memo.netComeOutWins++
-        hand.summary.netComeOutWins++
-        break
-      case 'comeout loss':
-        memo.comeOutLosses++
-        hand.summary.comeOutLosses++
-        memo.netComeOutWins--
-        hand.summary.netComeOutWins--
-        break
+  const sessionSummary = Object.assign({}, summaryTemplate)
+  const hands = []
+  const rules = {
+    minBet: 10,
+    maxOddsMultiple: {
+      4: 3,
+      5: 4,
+      6: 5,
+      8: 5,
+      9: 4,
+      10: 3
     }
+  }
 
-    if (Array.isArray(roll.payouts)) {
-      roll.payouts.forEach(p => {
-        if (p.type === 'place 6 win') {
-          memo.placeSixWins++
-          hand.summary.placeSixWins++
-        } else if (p.type === 'place 8 win') {
-          memo.placeEightWins++
-          hand.summary.placeEightWins++
-        }
-      })
+  for (let i = 0; i < numHands; i++) {
+    if (process.env.DEBUG) {
+      console.log(`\n================ HAND ${i + 1} ================`)
     }
+    const hand = playHand({ rules, bettingStrategy: minPassLineMaxOddsPlaceSixEight })
+    hand.summary = Object.assign({}, summaryTemplate)
+
+    sessionSummary.balance += hand.balance
+    hand.summary.balance = hand.balance
+
+    hand.history.reduce((memo, roll) => {
+      memo.rollCount++
+      hand.summary.rollCount++
+      memo.dist[roll.diceSum].ct++
+
+      switch (roll.result) {
+        case 'neutral':
+          memo.neutrals++
+          hand.summary.neutrals++
+          break
+        case 'point set':
+          memo.pointsSet++
+          hand.summary.pointsSet++
+          break
+        case 'point win':
+          memo.pointsWon++
+          hand.summary.pointsWon++
+          break
+        case 'comeout win':
+          memo.comeOutWins++
+          hand.summary.comeOutWins++
+          memo.netComeOutWins++
+          hand.summary.netComeOutWins++
+          break
+        case 'comeout loss':
+          memo.comeOutLosses++
+          hand.summary.comeOutLosses++
+          memo.netComeOutWins--
+          hand.summary.netComeOutWins--
+          break
+      }
 
-    if (roll.result === 'seven out') {
-      if (roll.betsBefore?.place?.six) {
-        memo.placeSixLosses++
-        hand.summary.placeSixLosses++
+      if (Array.isArray(roll.payouts)) {
+        roll.payouts.forEach(p => {
+          if (p.type === 'place 6 win') {
+            memo.placeSixWins++
+            hand.summary.placeSixWins++
+          } else if (p.type === 'place 8 win') {
+            memo.placeEightWins++
+            hand.summary.placeEightWins++
+          }
+        })
       }
-      if (roll.betsBefore?.place?.eight) {
-        memo.placeEightLosses++
-        hand.summary.placeEightLosses++
+
+      if (roll.result === 'seven out') {
+        if (roll.betsBefore?.place?.six) {
+          memo.placeSixLosses++
+          hand.summary.placeSixLosses++
+        }
+        if (roll.betsBefore?.place?.eight) {
+          memo.placeEightLosses++
+          hand.summary.placeEightLosses++
+        }
       }
-    }
 
-    return memo
-  }, sessionSummary)
+      return memo
+    }, sessionSummary)
+
+    hands.push(hand)
+  }
+
+  sessionSummary.handCount = hands.length
+
+  for (const k of Object.keys(sessionSummary.dist)) {
+    sessionSummary.dist[k].ref = Number((sessionSummary.dist[k].prob * sessionSummary.rollCount).toFixed(1))
+    sessionSummary.dist[k].diff = Number((sessionSummary.dist[k].ct - sessionSummary.dist[k].ref).toFixed(1))
+    sessionSummary.dist[k].diff_pct = Number((((sessionSummary.dist[k].ct - sessionSummary.dist[k].ref) / sessionSummary.dist[k].ref) * 100).toFixed(1))
+    if (showDetail) {
+      sessionSummary.dist[k].ref_work = `${(sessionSummary.dist[k].prob * sessionSummary.rollCount).toFixed(1)} (${sessionSummary.rollCount} * ${sessionSummary.dist[k].prob.toFixed(2)})`
+    }
+    delete sessionSummary.dist[k].prob
+  }
 
-  hands.push(hand)
+  return { sessionSummary, hands, rules }
 }
 
-sessionSummary.handCount = hands.length
+function printResults ({ sessionSummary, hands, showDetail, rules }) {
+  console.log(`[table rules] minimum bet: $${rules.minBet}`)
+
+  console.log('\nDice Roll Distribution')
+  console.table(sessionSummary.dist)
+  delete sessionSummary.dist
+
+  console.log('\nSession Summary')
+  console.table(sessionSummary)
+
+  console.log('\nHands Summary')
+  console.table(hands.map(hand => {
+    delete hand.summary.dist
+    return hand.summary
+  }))
 
-for (const k of Object.keys(sessionSummary.dist)) {
-  sessionSummary.dist[k].ref = Number((sessionSummary.dist[k].prob * sessionSummary.rollCount).toFixed(1))
-  sessionSummary.dist[k].diff = Number((sessionSummary.dist[k].ct - sessionSummary.dist[k].ref).toFixed(1))
-  sessionSummary.dist[k].diff_pct = Number((((sessionSummary.dist[k].ct - sessionSummary.dist[k].ref) / sessionSummary.dist[k].ref) * 100).toFixed(1))
   if (showDetail) {
-    sessionSummary.dist[k].ref_work = `${(sessionSummary.dist[k].prob * sessionSummary.rollCount).toFixed(1)} (${sessionSummary.rollCount} * ${sessionSummary.dist[k].prob.toFixed(2)})`
+    console.log('\nHands')
+    hands.forEach((hand, handNum) => {
+      console.log(`\nHand: ${handNum + 1}, Balance: $${hand.balance}`)
+      console.table(hand.history)
+    })
   }
-  delete sessionSummary.dist[k].prob
 }
-console.log('\nDice Roll Distribution')
-console.table(sessionSummary.dist)
-delete sessionSummary.dist
-
-console.log('\nSession Summary')
-console.table(sessionSummary)
-
-console.log('\nHands Summary')
-console.table(hands.map(hand => {
-  delete hand.summary.dist
-  return hand.summary
-}))
-
-if (showDetail) {
-  console.log('\nHands')
-  hands.forEach((hand, handNum) => {
-    console.log(`\nHand: ${handNum + 1}, Balance: $${hand.balance}`)
-    console.table(hand.history)
-  })
+
+if (require.main === module) {
+  const numHands = parseInt(process.argv[2], 10)
+  const showDetail = process.argv[3]
+  console.log(`Simulating ${numHands} Craps Hand(s)`)
+  console.log('Using betting strategy: minPassLineMaxOddsPlaceSixEight')
+  const result = simulateHands(numHands, showDetail)
+  printResults({ ...result, showDetail })
+} else {
+  module.exports = simulateHands
 }