diff --git a/exercises/converting_decimals_to_percents.html b/exercises/converting_decimals_to_percents.html
index 3c602abe5..98960649b 100644
--- a/exercises/converting_decimals_to_percents.html
+++ b/exercises/converting_decimals_to_percents.html
@@ -15,7 +15,7 @@
             </div>
             <p>Express the decimal as a percent.</p>
             <p class="question"><code><var>DECIMAL</var></code></p>
-            <p class="solution" data-forms="percent"><var>PERCENT</var></p>
+            <p class="solution" data-forms="percent"><var>DECIMAL</var></p>
             <div class="hints">
                 <div>
                     <p>Rewrite the decimal as a fraction with a denominator of 100.</p>
diff --git a/exercises/empirical_rule.html b/exercises/empirical_rule.html
index a12a5d9b5..4f7a790fe 100644
--- a/exercises/empirical_rule.html
+++ b/exercises/empirical_rule.html
@@ -51,7 +51,7 @@
                     <code><var>roundTo( 1, MEAN + STDDEV * Z )</var></code> years.
                 </p>
 
-                <div class="solution" data-forms="percent"><var>ANSWER</var></div>
+                <div class="solution" data-forms="percent"><var>ANSWER / 100</var></div>
 
                 <div class="hints">
                     <p>We can try to estimate using the empirical rule, also known as the 68-95-99.7 percent rule.</p>
@@ -396,7 +396,7 @@
                     <code><var>roundTo( 1, MEAN + STDDEV * Z1 )</var></code> and <code><var>roundTo( 1, MEAN + STDDEV * Z2 )</var></code> years.
                 </p>
 
-                <div class="solution" data-forms="percent"><var>AREA</var></div>
+                <div class="solution" data-forms="percent"><var>AREA / 100</var></div>
 
                 <div class="hints" data-apply="appendContents">
                     <div id="hintGoal">
diff --git a/exercises/independent_probability.html b/exercises/independent_probability.html
index eadbeadec..a336cb491 100644
--- a/exercises/independent_probability.html
+++ b/exercises/independent_probability.html
@@ -41,7 +41,7 @@
                 If you flip a coin and roll a 6-sided die, what is the probability that you will flip a <var>HT</var> and roll <var>RESULT_DESC</var>?
             </p>
 
-            <div class="solution" data-forms="proper, decimal"><var>0.5 * RESULT_POSSIBLE.length / 6</var></div>
+            <div class="solution" data-forms="proper, decimal, percent"><var>0.5 * RESULT_POSSIBLE.length / 6</var></div>
 
             <div class="hints">
                 <p>
@@ -408,7 +408,7 @@
                 If both fire their cannons at the same time, what is the probability that <var>QUESTION</var>?
             </p>
 
-            <div class="solution" data-forms="proper, decimal"><var>ANSWER</var></div>
+            <div class="solution" data-forms="proper, decimal, percent"><var>ANSWER</var></div>
 
             <div class="hints">
                 <p>
diff --git a/exercises/percentage_word_problems_1.html b/exercises/percentage_word_problems_1.html
index 0355f1cc1..1dd246fae 100644
--- a/exercises/percentage_word_problems_1.html
+++ b/exercises/percentage_word_problems_1.html
@@ -42,7 +42,7 @@
             </div>
             <p class="question">
                 <var>person(1)</var> has <var>BANK_MORE</var> dollars in the bank today. Yesterday, <var>he(1)</var> had <var>BANK_FEWER</var> dollars in the bank. By what percentage did <var>person(1)</var>'s bank account increase over the past day? (Round your answer to the nearest hundredth of a percent.)</p>
-            <p class="solution" data-forms="percent"><var>round(((BANK_MORE - BANK_FEWER) * 10000) / BANK_FEWER) / 100</var></p>
+            <p class="solution" data-forms="percent"><var>roundTo(4, (BANK_MORE - BANK_FEWER) / BANK_FEWER)</var></p>
             <div class="hints">
                 <p>The bank account grew by <code><var>BANK_MORE</var> - <var>BANK_FEWER</var> = <var>BANK_MORE - BANK_FEWER</var></code> dollars </p>
                 <p><code>\frac{<var>BANK_MORE - BANK_FEWER</var>}{<var>BANK_FEWER</var>} \approx <var>round(((BANK_MORE - BANK_FEWER) * 10000) / BANK_FEWER) / 100</var>\%</code></p>
@@ -51,7 +51,7 @@
         <div id="bank-percentages-loss" data-type="bank-percentages">
             <p class="question">
                 <var>person(1)</var> has <var>BANK_FEWER</var> dollars in the bank today. Yesterday, <var>he(1)</var> had <var>BANK_MORE</var> dollars in the bank. By what percentage did <var>person(1)</var>'s bank account decrease over the past day? (Round your answer to the nearest hundredth of a percent.)</p>
-            <p class="solution" data-forms="percent"><var>round(((BANK_MORE - BANK_FEWER) * 10000) / BANK_MORE) / 100</var></p>
+            <p class="solution" data-forms="percent"><var>roundTo(4, (BANK_MORE - BANK_FEWER) / BANK_MORE)</var></p>
             <div class="hints">
                 <p>The bank account decreased by <code><var>BANK_MORE</var> - <var>BANK_FEWER</var> = <var>BANK_MORE - BANK_FEWER</var></code> dollars </p>
                 <p><code>\frac{<var>BANK_MORE - BANK_FEWER</var>}{<var>BANK_MORE</var>} \approx <var>round(((BANK_MORE - BANK_FEWER) * 10000) / BANK_MORE) / 100</var>\%</code></p>
diff --git a/exercises/z_scores_2.html b/exercises/z_scores_2.html
index d30075359..9559cf845 100644
--- a/exercises/z_scores_2.html
+++ b/exercises/z_scores_2.html
@@ -69,8 +69,8 @@
             <div class="fake_row reading" data-each="ROWS as i, row">
                 <span><var>row</var></span><span data-each="ZGRID[i] as j, zgrid"><var>zgrid</var></span>
             </div>
-            <div class="solution" data-inexact data-max-error="0.01" data-forms="percent">
-                <span><var>roundTo(2, ANSWER * 100)</var></span>
+            <div class="solution" data-inexact data-max-error="0.0001" data-forms="percent">
+                <span><var>roundTo(4, ANSWER)</var></span>
             </div>
 
             <div class="hints">
diff --git a/exercises/z_scores_3.html b/exercises/z_scores_3.html
index ab669fa88..07f0e1c6c 100644
--- a/exercises/z_scores_3.html
+++ b/exercises/z_scores_3.html
@@ -106,8 +106,8 @@
             <div class="fake_row reading" data-each="ROWS as i, row">
                 <span><var>row</var></span><span data-each="ZGRID[i] as j, zgrid"><var>zgrid</var></span>
             </div>
-            <div class="solution" data-inexact data-max-error="0.01" data-forms="percent">
-                <span><var>roundTo( 2, ANSWER * 100 )</var></span>
+            <div class="solution" data-inexact data-max-error="0.0001" data-forms="percent">
+                <span><var>roundTo(4, ANSWER)</var></span>
             </div>
 
             <div class="hints">
diff --git a/utils/answer-types.js b/utils/answer-types.js
index d62867663..6337c1299 100644
--- a/utils/answer-types.js
+++ b/utils/answer-types.js
@@ -211,6 +211,15 @@ Khan.answerTypes = $.extend(Khan.answerTypes, {
             }, $(solution).data());
             var acceptableForms = options.forms.split(/\s*,\s*/);
 
+            // If percent is an acceptable form, make sure it's the last one
+            // in the list so we don't prematurely complain about not having
+            // a percent sign when the user entered the correct answer in a
+            // different form (such as a decimal or fraction)
+            if (_.contains(acceptableForms, "percent")) {
+                acceptableForms = _.without(acceptableForms, "percent");
+                acceptableForms.push("percent");
+            }
+
             // Take text looking like a fraction, and turn it into a number
             var fractionTransformer = function(text) {
                 text = text
@@ -374,6 +383,7 @@ Khan.answerTypes = $.extend(Khan.answerTypes, {
                     var transformed = forms.decimal(text);
                     $.each(transformed, function(ix, t) {
                         t.exact = hasPercentSign;
+                        t.value = t.value / 100;
                     });
                     return transformed;
                 },