Puzzles
Blackboard sums
The numbers 1 to 20 are written on a blackboard. Each turn, you may erase two numbers, \(a\) and \(b\) and write the sum \(a+b\) in their place. You continue until only one number remains.
What is the largest number you can make?
If you enjoyed this puzzle, check out Sunday Afternoon Maths LV,
puzzles about numbers, or a random puzzle.
puzzles about numbers, or a random puzzle.