Sunday Times Teaser 3044 – Building Blocks
by Colin Vout
Published Sunday January 24 2021 (link)
The kids had used all the blocks each of them owned (fewer than 100 each) to build triangular peaks — one block on the top row, two on the next row, and so on.
“My red one’s nicer!” “My blue one’s taller!”
“Why don’t you both work together to make one bigger still?” I said. I could see they could use all these blocks to make another triangle.
This kept them quiet until I heard, “I bet Dad could buy some yellow blocks to build a triangle bigger than either of ours was, or a red and yellow triangle, or a yellow and blue triangle, with no blocks ever left over.”
This kept me quiet, until I worked out that I could.
How many red, blue and yellow blocks would there be?