Working-Memory Sums
Pick tiles that hit the target exactly
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What is the Working-Memory Sums?
Working-memory sums ask you to add several numbers in your head while keeping track of the total so far. In the Neuroptimize version, you pick tiles from a grid so that their values add up to an exact target number. It combines quick addition with a search for the right combination, similar to a subset sum puzzle.
Mental addition of several numbers is often used in research to illustrate how working memory is used. Working memory is the limited-capacity system that holds information briefly while you work with it. Each time you add a tile, you have to hold the running total, compare it with the target and decide what is still missing. The Working-Memory Sums game turns this into a 60-second race to hit as many targets as you can.
How to play the Working-Memory Sums
- A target number appears at the top, with a grid of numbered tiles below it. You have 60 seconds to hit as many targets as you can.
- Tap tiles to add them to your selection. Tap a selected tile again to remove it. You need at least two tiles, and any combination that adds up to the target exactly counts.
- If your selection reaches or passes the target without hitting it exactly, that counts as a mistake and your selection is cleared so you can try again. You can also tap Skip for a new puzzle, but a skip also counts as a mistake.
- At low levels a running sum and progress bar show your total. From level 12 the sum is hidden and you only see how many tiles you have selected, so you must keep the total in your head.
- The grid grows from 6 tiles to 8, 9 and then 12 as your level rises, and the tile values get bigger.
- Below level 10 the target is made from two tiles. Higher levels need three tiles, and from level 26 the planted answer uses four. Solutions with more tiles score more points.
Strategies and tips
Start with the biggest tile
Pick the largest tile that fits well under the target, then work out what is left. If the target is 83 and you take 47, you now need 36. Looking for one specific number is easier than testing pairs at random.
Match the last digit
For a two-tile target, the last digits must add up to the last digit of the target. For 83, a tile ending in 7 pairs with one ending in 6, and one ending in 5 pairs with one ending in 8. Scan for these pairs before checking the tens.
Say the remainder, not the total
Once the sum is hidden, it helps to track what you still need rather than what you have. Start from the target and subtract each tile as you tap it. When the remainder matches a tile on the board, you know your final pick.
Undo instead of busting
Going over the target costs a mistake and clears everything. If you realise a tile was wrong, tap it again to deselect it. This keeps your progress and your accuracy.
Skip only when stuck
Every puzzle has at least one exact solution, so a skip is never needed to escape an impossible board. Because a skip counts as a mistake, use it only when you have spent a long time without finding the combination.
The science behind the Working-Memory Sums
Adding several numbers mentally requires holding intermediate results in working memory while further calculations are carried out. Working memory is a limited-capacity system for temporarily storing and manipulating information.
Frequently asked questions
Is there always a solution?
Yes. Every puzzle is built around a planted set of tiles that adds up to the target. Other combinations that hit the target exactly also count, as long as you use at least two tiles.
Why did the running total disappear?
From level 12, the game stops showing your current sum and shows only how many tiles you have selected. This makes you hold the total in working memory, which is the point of the task at higher levels.
What counts as a mistake in Working-Memory Sums?
Reaching or passing the target without hitting it exactly counts as a mistake, as does skipping a puzzle. Deselecting a tile by tapping it again is free.
What does working memory have to do with adding numbers?
When you add several numbers in your head, you have to hold the result so far while doing the next step. Working memory is the system that keeps that information available for a short time, and it can only hold a limited amount at once.