Computer science · Grades 6–8
Digital literacy · Formula sheet
Rules, conditions and small examples in one printable reference.
Remember this
Bits and bytes
A bit is a binary digit; a byte contains eight bits.
1 byte = 8 bits
9696 × 8 = 77568
Uncompressed storage models
This simple model excludes metadata and compression.
size = rows × columns × bytes per cell
39 × 131 × 3 = 15327
Compare compressed sizes
Use the same size units; file-size reduction alone does not prove quality is preserved.
saved % = (original − compressed)/original × 100
(1480 − 444)/1480 × 100 = 70%
Pixel counts
Count the individual picture elements in a rectangular image.
pixels = width × height
320 × 300 = 96000
Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.