Rounding Game
'Roll the dice , make your number, round it and see who is closest to 50'
This is a really simple but engaging game to help practise rounding to a given number of decimal places! Use 10 sided dice to generate some random numbers for you. In the first instance, roll 3, 10 sided dice (or 1, 3 times) and make a number between 0 and 10 with the result. Round this number to 1 decimal place and then add it to your total. You get ten turns and the object is to get a number that is as close to possible to 50 by the end of your 10th turn! You can use the spreadsheet applet below or you can play with pencil and paper with the activity sheet to get more practise of adding and subtracting decimals. Watch the video explanation below to see an example of a game in action.
Resources
Use the the spreadsheet applet below to play online or this 
Rounding game activity sheet to play with pencil and paper! You need access to some 10 sided dice. Otherwise you can use one of the following simulators, 
Virtual customisable dice (you can make a 10 sided die that goes from 0 to 9 and roll it three times), Dice simulator (This generates 3 dice rolls simultaneously). Check out 
the Dice Shop if you need to buy some dice, although there are plenty of sources.
The rules
- Roll 3, 10 sided dice (or 1, 3 times). Note, if the dice go from 1 to 10 then count 10 as zero.
- Arrange the 3 digits to make a number between 0 and 10. For example, if you rolled a 3, 5 and 1 then you can make 3.51, 3.15, 5.31, 5.13, 1.53, or 1.35. Add this number in the 'Dice column' for turn 1.
- Round this number to 1 decimal place and then add this number to the 'Rounded to 1 dp' column.
- This becomes your new total.
- Repeat for turn 2 and then add or subtract your second, rounded number to or from your previous total to make the new total.
- Repeat for ten turns. If playing with two players then take turns to roll the dice until you have had ten turns each.
- The winner is the one whose total is closest to 50 at the end of ten turns.
Note that the game can easily be adapted to rounding to 2 decimal places by rolling the dice four times.
Spreadsheet applet
This spreadsheet applet is set up for two players to play the game online! Just enter your numbers in the 'Dice' and 'Rounded' columns. The rest of the calculations are done for you!
Description
- Decide whether to play online with the spreadsheet applet or with paper and pencil using the activity sheet.
- Students roll three, ten sided dice - or one dice three times.
- Let ten count as zero.
- Use the three results to generate a number between 0 and 10. Put the digits in any order with a decimal place after the first.
- Students take turns to do this ten times, adding or subtracting each number from the previous total.
- The winner is the closest to 50.
- The game can then be adapted to working with two decimal places by rolling the dice 4 times.
Note for Teachers
Paper or computer?
- The spreadsheet applet is set up to do the addition/subtraction automatically. This is so that the exercise is about rounding and strategy. Students have to decide which order to put the digits in such that the rounded answer will be desirable. In fact the mental arithmetic really needs to be done before students make their decisions.
- The paper version of the activity requires students to do their own additon/subtraction, thus adding an extra feature to the activity. Obviously calculators can be allowed if teachers find it appropriate.
- Essentially the game is about rounding but it involves a good deal of strategy and mental arithmetic given the random digits from the dice.