bit shifting arithmetic

Back to your original example:

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Basically, I don't want to deal with floating points, so I have a problem that was originally

400 * 0.0615 = 24.6

to this

(400*615) >> 4 = 24.6

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Instead of multiplying 0.0615 by 10000, multiply by a power of 2. For example:

= 400 * (0.0615 * 2^16) >> 16

= 400 * 4030 >> 16

= 1612000 >> 16

= 24

If you want to avoid floats and still have fractional values, you will have to use fixed point.