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Negative numbers in binary

Demo lesson, about 14 min, +25 XP

Games are full of numbers below zero. Buying a sword changes Nico's gold by -25. A skeleton two tiles to the left of the hero sits at x = -2. Memory has no minus sign, though. It only has bits. So how does a computer store -25?

The last two lessons left two puzzles open. In Bit flags, ~Burning printed -3. In Shifting bits, 1 << 31 printed -2147483648. You also saw int.MaxValue + 1 turn into int.MinValue back in C# Basics. All of them come from one rule, and this lesson is about that rule.

Read the rest of this lesson and run the code in your browser.

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