Friday 26 September 2014

Target *


Instructions:

Choose a number between 25 and 55.
Take turns placing a marker on top of the numbers on the board below.
Each time add the number to the running total.
Each square can be used only once.
Try to be the player to reach the target exactly.
  
 
 


5

5

5

5

5

4

4

4

4

4

3

3

3

3

3

2

2

2

2

2

1

1

1

1

1
 
 
Variation: 
  • For younger children choose a smaller target number and perhaps only use a board with 1s, 2s and 3s.
  • Pick a number and work backwards to 0.
 
 
Helpful Hint:
You can use a counter on a Hundreds Square to keep track of your sum.  It may also help you to see how much more you would like to add on.
 

The Correct Order Solution

a)  2  4  1  3

b)  4  3  1  2

c)  2  3  1  5  4     or      4  3  1  5  2

Friday 19 September 2014

Rabbit Problem Solution


Apologies...  I just realized that I didn't post the solution to the rabbit problem last week.  Here it is:


It takes the rabbit 28 days to climb out of the hole.
 
The first thing to notice is that the act of climbing and sliding can be greatly simplified.  Instead of thinking of going up 3 metres and down 2 metres every day, you can just think about it as going up 1 metre.  So every day the rabbit goes up 1 metre – which should mean that it takes her 30 days to get out, 1 metre each day.  But the reason it does not is that on the day the rabbit actually gets out, she doesn’t slip back down 2 metres.  The rabbit saves itself two days, and it only takes 28 days.

The Correct Order ****


You need to place the numbers in the correct order according to the clues given.  For each problem the numbers may not be in the place that relates to their value.  For example, 1 cannot be in the first position, 2 cannot be in the second place, 3 cannot be in the third place…and so on.


 a) Using 1  2  3  and  4:

  • The four is directly to the right of the two.
  • The first number and the last number add up to five.

b) Using 1  2  3  and  4:

  • The even numbers are not next to each other.
  • The 1 is directly to the right of the 3.

c) Using 1  2  3  4  and  5:

  • The first and fifth cards add to 6.
  • The third and fourth cards add to 6.
  • The second and third cards add to 4.

Helpful tip:  Write the numbers on little pieces of paper (or use playing cards) so that you can move them around easily as you try out your ideas.

 

Friday 12 September 2014

Make Fifteen **



Equipment:    

  • calculator
  • 20 counters (of keep a tally of points)

 Instructions:

  • Player 1 enters any number 0-20 on the calculator and hands the calculator to Player 2, and says “Make 15.”
  • Player 2 looks at the display and thinks of a number that can be added or subtracted from the displayed number to make a total of fifteen.
  • Player 2 presses + or -, the number to be added or subtracted, and =.
  • If the answer is 15, Player 2 earns one counter.  If the answer is not 15, Player 2 does not score.
  • Players reverse roles.
  • The first player to earn 10 counters wins the game.

 Variation:

  • Player take turns to “Make Eight,” “Make Twelve,” “Make Twenty,” etc.

Thursday 11 September 2014

Rabbit Problem Hint


The answer is not 30.  Think carefully about what happens near the end of the rabbit’s climb to the top.

Friday 5 September 2014

Welcome to the Weekly Maths Challenge!


Each week I will post a maths challenge or activity which you can solve with your family and friends.  I will post the solution to each challenge the following week.

The level of difficulty will change from week to week.  I will give each activity a star grading from « to ««««« with the level of difficulty increasing with the number of stars.  This star grading is simply a guide.

Here is the first challenge:
 
The Rabbit Puzzle «««

A rabbit falls into a dry well 30 metres deep.  Since being at the bottom of a well was not her original plan, she decides to climb out.  When she attempts to do so, she finds that after going up 3 metres, she slips back 2.  Frustrated, she stops where she is for the day and resumes her efforts the following morning – with the same result.  How many days does it take her to get out of the well?

(In a few days I will post a hint for you to check that you are on the right track to the solution.)

Enjoy,
Sarah Hopkins