math challenge

Week of May 27 to June 2, 1996

The Monarch's Trial

In the country where Xandra lives, a new monarch is chosen every year. The decision is made by determining which of the youth of the nation performs the best in a series of rigorous intellectual tests.

Xandra begins her trial with the following question:

The digits 1 2 3 4 5 6 7 8 9 can be made to equal 30, if the appropriate minus and plus signs are placed between the digits.

As an example, you can make 77 in the following way: 12 + 34 - 56 + 78 + 9 = 77.

Xandra has an even better chance of succeeding in her quest if she can find a way to make the digits 1 to 9 equal 100.

Can you find more than one way to make the digits equal 30, or equal 100?

See the solution