Cleave Books
Puzzle Trio 3

7. It is possible to write down the digits 1 to 9 (writing each once and once only, and in order) and then place ordinary arithmetical signs as necessary so that the answer to the entire sum is 100.
For example -
1 × 2 + 34 + 56 + 7 - 8 + 9 = 100
and there several other ways it can be done.
Find a way that uses only + and - signs

8. "How old are you?"
"Well I forget exactly, but I do remember that my brother is two years older than I, … my sister is four years older than he, and … um, mother was twenty eight when I was born. … Oh, and my sister recently said that the average age of the four of us is seventy-four."
How old was he?

9. Kerry and Nick were going to cut the grass on their square lawn. They agreed that each should cut one-half of the area.
Kerry went first and cut a border 2 metres wide all the way around.
After doing a few sums, Nicki agreed that exactly one-half had been cut and happily cut the rest.
What was the area of the lawn?

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