Number Sense and Estimation Games

About this category

You do not need to count to know that one queue is longer than another or that a bag of apples is nearly full. People, babies and many animals have a built-in sense for approximate quantities. The nine games in this category train that sense and the estimation skills built on top of it.

Dot Flash and Dot Compare test the raw feeling for numerosity. Gut Total, Number Sense and How Much More? ask for sums, counts and differences from a brief look. Fair Share turns a bar into a head count, What Feels Right? looks for the next number in a sequence, Closer To compares mental calculations, and Gut Odds asks for chances in percent.

All answers are checked against exact values, and each round ends with a short note that explains how the answer comes about.

The 9 Quantity games

Why train this?

Number sense is more than arithmetic. It is the ability to see whether an answer is plausible, to judge a quantity at a glance and to reason with proportions and chances. Studies of adult skills find that such judgements matter for personal finances, health decisions and the reading of news, even for people who calculate with ease.

The nice thing about this kind of intuition is that it responds to feedback. A few minutes of play with real numbers is enough to notice a pattern in your errors, for example that you overestimate large swarms or underestimate the chance of at least one success.

How to improve

• Do not count. For swarms and flashes, take in the whole picture and trust your first impression.
• Round numbers to friendly values like 10, 25 or 50, and then correct a little.
• Think in fractions of a whole: a half, a quarter, a tenth are easy to compute.
• For chances, count outcomes or compute the chance of the opposite event.
• Use the bias statistic on the Stats page. A consistent high or low tendency is easy to correct.
• Play the hardest levels in short runs. Estimation gets worse when you are tired.

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