diff --git a/davtelepot/messages.py b/davtelepot/messages.py
index b461363..9b0921a 100644
--- a/davtelepot/messages.py
+++ b/davtelepot/messages.py
@@ -1028,6 +1028,14 @@ default_useful_tools_messages = {
             'en': "calculate",
             'it': "calcola",
         },
+        'use_buttons': {
+            'en': "Use buttons to enter an algebraic expression.\n\n"
+                  "<i>The input will be displayed after you stop typing for a "
+                  "while.</i>",
+            'it': "Usa i pulsanti per comporre un'espressione algebrica.\n\n"
+                  "<i>L'espressione verrà mostrata quando smetterai di "
+                  "digitare per un po'.</i>",
+        },
     },
     'info_command': {
         'description': {
diff --git a/davtelepot/useful_tools.py b/davtelepot/useful_tools.py
index 9584a14..bb9e600 100644
--- a/davtelepot/useful_tools.py
+++ b/davtelepot/useful_tools.py
@@ -1,8 +1,10 @@
 """General purpose functions for Telegram bots."""
 
 # Standard library
+import asyncio
 import datetime
 import json
+import logging
 
 from collections import OrderedDict
 from typing import List, Union
@@ -17,17 +19,17 @@ from .utilities import (get_cleaned_text, get_user, make_button,
 
 def get_calc_buttons() -> OrderedDict:
     buttons = OrderedDict()
-    buttons['pow'] = dict(
+    buttons['**'] = dict(
         value='**',
         symbol='**',
         order='A1',
     )
-    buttons['floordiv'] = dict(
+    buttons['//'] = dict(
         value='//',
         symbol='//',
         order='A2',
     )
-    buttons['mod'] = dict(
+    buttons['%'] = dict(
         value='%',
         symbol='mod',
         order='A3',
@@ -39,85 +41,85 @@ def get_calc_buttons() -> OrderedDict:
     )
     buttons[0] = dict(
         value=0,
-        symbol='0️⃣',
+        symbol='0',
         order='E1',
     )
     buttons[1] = dict(
         value=1,
-        symbol='1️⃣',
+        symbol='1',
         order='D1',
     )
     buttons[2] = dict(
         value=2,
-        symbol='2️⃣',
+        symbol='2',
         order='D2',
     )
     buttons[3] = dict(
         value=3,
-        symbol='3️⃣',
+        symbol='3',
         order='D3',
     )
     buttons[4] = dict(
         value=4,
-        symbol='4️⃣',
+        symbol='4',
         order='C1',
     )
     buttons[5] = dict(
         value=5,
-        symbol='5️⃣',
+        symbol='5',
         order='C2',
     )
     buttons[6] = dict(
         value=6,
-        symbol='6️⃣',
+        symbol='6',
         order='C3',
     )
     buttons[7] = dict(
         value=7,
-        symbol='7️⃣',
+        symbol='7',
         order='B1',
     )
     buttons[8] = dict(
         value=8,
-        symbol='8️⃣',
+        symbol='8',
         order='B2',
     )
     buttons[9] = dict(
         value=9,
-        symbol='9️⃣',
+        symbol='9',
         order='B3',
     )
-    buttons['plus'] = dict(
+    buttons['+'] = dict(
         value='+',
-        symbol='➕️',
+        symbol='+',
         order='B4',
     )
-    buttons['minus'] = dict(
+    buttons['-'] = dict(
         value='-',
-        symbol='➖',
+        symbol='-',
         order='C4',
     )
-    buttons['times'] = dict(
+    buttons['*'] = dict(
         value='*',
-        symbol='✖️',
+        symbol='*',
         order='D4',
     )
-    buttons['divided'] = dict(
+    buttons['/'] = dict(
         value='/',
-        symbol='➗',
+        symbol='/',
         order='E4',
     )
-    buttons['point'] = dict(
+    buttons['.'] = dict(
         value='.',
         symbol='.',
         order='E2',
     )
-    buttons['000'] = dict(
+    buttons['*1000'] = dict(
         value='*1000',
-        symbol='0️⃣0️⃣0️⃣',
+        symbol='000',
         order='E3',
     )
-    buttons['enter'] = dict(
+    buttons['\n'] = dict(
         value='\n',
         symbol='✅',
         order='F1',
@@ -133,14 +135,16 @@ def get_calc_buttons() -> OrderedDict:
 calc_buttons = get_calc_buttons()
 
 
-def get_calculator_keyboard():
+def get_calculator_keyboard(additional_data: list = None):
+    if additional_data is None:
+        additional_data = []
     return make_inline_keyboard(
         [
             make_button(
                 text=button['symbol'],
                 prefix='calc:///',
                 delimiter='|',
-                data=[button['value']]
+                data=[*additional_data, button['value']]
             )
             for button in sorted(calc_buttons.values(), key=lambda b: b['order'])
         ],
@@ -149,24 +153,41 @@ def get_calculator_keyboard():
 
 
 async def _calculate_button(bot: Bot,
+                            update: dict,
+                            user_record: OrderedDict,
                             language: str,
                             data: List[Union[int, str]]):
-    result, text, reply_markup = '', '', None
-    if len(data) == 1:
-        input_value = data[0]
-        if input_value == 'del':
-            pass
-        elif input_value == 'info':
-            pass
-        elif input_value in [button['value'] for button in calc_buttons.values()]:
-            pass
+    text, reply_markup = '', None
+    if update['from']['id'] not in bot.shared_data['calc']:
+        bot.shared_data['calc'][update['from']['id']] = []
+        if len(data) < 2:
+            record_id = bot.db['calculations'].insert(
+                dict(
+                    user_id=user_record['id'],
+                    created=datetime.datetime.now()
+                )
+            )
+            data = [record_id, *data]
         else:
-            pass  # Error!
+            record_id = data[0]
+        asyncio.ensure_future(
+            calculate_session(bot=bot,
+                              user_telegram_id=update['from']['id'],
+                              language=language,
+                              data=data)
+        )
+        text = bot.get_message(
+            'useful_tools', 'calculate_command', 'use_buttons',
+            language=language
+        )
+        reply_markup = get_calculator_keyboard(additional_data=[record_id])
+    update['data'] = data
+    bot.shared_data['calc'][update['from']['id']].append(update)
     # Edit the update with the button if a new text is specified
     if not text:
-        return result
+        return
     return dict(
-        text=result,
+        text='',
         edit=dict(
             text=text,
             reply_markup=reply_markup
@@ -174,6 +195,64 @@ async def _calculate_button(bot: Bot,
     )
 
 
+async def calculate_session(bot: Bot,
+                            user_telegram_id: int,
+                            language: str,
+                            data: List[Union[int, str]]):
+    queue = bot.shared_data['calc'][user_telegram_id]
+    queue_len = None
+    while queue_len != len(queue):
+        queue_len = len(queue)
+        await asyncio.sleep(2)
+    last_entry = max(queue, key=lambda u: u['id'])
+    # Remove user queue
+    queue = queue.copy()
+    del bot.shared_data['calc'][user_telegram_id]
+
+    record = None
+    text, reply_markup = '', None
+
+    # It would be nice to do:
+    # for update in sorted(queue, key=lambda u: u['id'])
+    # Alas, 'id's are not progressive... Telegram's fault!
+    for i, update in enumerate(queue):
+        if i % 5 == 0:
+            await asyncio.sleep(.1)
+        data = update['data']
+        if len(data) != 2:
+            logging.error(f"Something went wrong: invalid data received.\n{data}")
+            return
+        if not text:
+            record = bot.db['calculations'].find_one(
+                id=data[0]
+            )
+            text = record['text'] or ''
+            reply_markup = get_calculator_keyboard(additional_data=[record['id']])
+        input_value = data[1]
+        if input_value == 'del':
+            pass
+        elif input_value == 'info':
+            pass
+        elif input_value in calc_buttons:
+            text = f"{text} {calc_buttons[input_value]['value']}"
+        else:
+            pass  # Error!
+    if record:
+        bot.db['calculations'].update(
+            dict(
+                id=record['id'],
+                modified=datetime.datetime.now(),
+                text=text
+            ),
+            ['id']
+        )
+    await bot.edit_message_text(
+        text=text,
+        update=last_entry,
+        reply_markup=reply_markup
+    )
+
+
 async def _calculate_command(bot: Bot,
                              update: dict,
                              language: str,
@@ -339,6 +418,29 @@ def init(telegram_bot: Bot, useful_tools_messages=None):
         useful_tools_messages
     )
     telegram_bot.messages['useful_tools'] = useful_tools_messages
+    telegram_bot.shared_data['calc'] = dict()
+
+    if 'calculations' not in telegram_bot.db.tables:
+        types = telegram_bot.db.types
+        table = telegram_bot.db.create_table(
+            table_name='calculations'
+        )
+        table.create_column(
+            'user_id',
+            types.integer
+        )
+        table.create_column(
+            'created',
+            types.datetime
+        )
+        table.create_column(
+            'modified',
+            types.datetime
+        )
+        table.create_column(
+            'text',
+            types.string
+        )
 
     @telegram_bot.command(command='/calc',
                           aliases=None,
@@ -358,8 +460,10 @@ def init(telegram_bot: Bot, useful_tools_messages=None):
     @telegram_bot.button(prefix='calc:///',
                          separator='|',
                          authorization_level='everybody')
-    async def calculate_button(bot, language, data):
-        return await _calculate_button(bot=bot, language=language, data=data)
+    async def calculate_button(bot, update, user_record, language, data):
+        return await _calculate_button(bot=bot, user_record=user_record,
+                                       update=update,
+                                       language=language, data=data)
 
     @telegram_bot.command(command='/info',
                           aliases=None,