Irish Times Maths Week Puzzles

Leaping Frogs

 Maths Week Puzzle from the Irish Times Wednesday 14th 2009

This is popular logistics problem that can be enjoyed as a game. Seven lily pads aligned in a straight line float on a pond. Six of the lilies have each a frog on them, with the centre lily empty and each frog faces the centre. The three frogs on the left are male and the three frogs on the right are female. A frog can jump onto the next pad if it is free or jump over one other frog onto a free lily pad. As an added proviso frogs can only jump forward. How can the male and female frogs change side? It will be fun to try using six coins, perhaps three one euro and three two euro coins.

There are 15 jumps required. Click here to see how its done...

Making 100

puzzle from Tuesday 13th  

IT IS possible to make up 100 using all the digits 1 through 10 (10 may be used as 10 or 1 and 0). You can insert operators (plus, minus, multiply and divide) between them as you wish, but you must use all the digits only once and in that order.

For example, 123 plus 45 minus 67 plus 8 minus 9 times 1 plus 0 equals 100. How many more ways can you find to make 100?

I dont know how many ways you can make up 100, but I gave up after these:

123+45-67+8-9x1+0 = 100

1x2+3-4-5+6+7-8+9x10 = 100

1x2x3x4x5-6-7-8-9+10 = 100

12x3+45-6+7+8+9+1+0 = 100

12-3-4-5-6+7+89+10 = 100

1-2-3-4+5+6+78+9+10 = 100

Hadn't time to do any more what with there being so many events on for Maths Week, but the first rainy day....

If you've more send in your list and we'll post them.

www.mathsweek@wit.ie