Measurement multiplication factors designation in SI Units Yocto (y) Refers to 10-24 factor in SI units (1 yocto m = 0.000000000000000000000001 m) Zepto (z) Refers to 10-21 factor in SI units (1 zepto m = 0.000000000000000000001 m) Atto (a) Refers to 10-18 factor in SI units (1 atto m = 0.000000000000000001 m) Femto (f) Refers to 10-15 factor in SI units (1 femto m = 0.000000000000001 m) Pico (p) Refers to 10-12 factor in SI units (1 pico m = 0.000000000001 m) Nano (n) Refers to 10-9 factor in SI units (1 nano m= 0.000000001 m) Micro (μ) Refers to 10-6 factor in SI units (1 μm = 0.000001 m) Milli (m) Refers to 10-3 factor in SI units (1 mm = 0.001 m) Centi (c) Refers to 10-2 factor in SI units (1 cm = 0.01 m) Deci (d) Refers to 10-1 factor in SI units (1 deci m = 0.1 m) Deca (da) Refers to 101 factor in SI units (1 decameter = 10 m) Hecto (h) Refers to 102 factor in SI units (1 hectometer = 100 m) Kilo (k) Refers to 103 factor in SI units (1 km = 1000 m) Mega (M) Refers to 106 factor in SI units (1 MHz = 1000000 Hz) Giga (G) Refers to 109 factor in SI units (1 GHz = 1000000000 Hz) Tera (T) Refers to 1012 factor in SI units (1 TB = 1000000000000 bytes) Peta (P) Refers to 1015 factor in SI units (1 PB = 1000000000000000 bytes) Exa (E) Refers to 1018 factor in SI units (1 EB = 1000000000000000000 bytes) Zetta (Z) Refers to 1021 factor in SI units (1 ZB = 1000000000000000000000 bytes) Yotta (Y) Refers to 1024 factor in SI units (1Y byte = 1000000000000000000000000 bytes)

 Reference: 1. Bureau International des Poids et Mesures BIPM (SI Units) 2. Designation of Frequency 3. Designation of Memory/Data Storage 4. System of Units Unit of Measure (UOM) 5. Large Number Designation