KH-->MH-->GH-->PH/s. We're going to run out of letters!
SI Prefixes
Multiple Prefix Symbol Example
1,000,000,000,000,000,000 (1018) exa- E Eg (exagram)
1,000,000,000,000,000 (1015) peta- P PJ (petajoule)
1,000,000,000,000 (1012) tera- T TV (teravolt)
1,000,000,000 (109) giga- G GW (gigawatt)
1,000,000 (106) mega- M MHz (megahertz)
1,000 (103) kilo- k kg (kilogram)
100 (102) hecto- h hm (hectometer)
10 (101) deka- da daN (dekanewton)
1/10 (10–1) deci- d dC (decicoulomb)
1/100 (10–2) centi- c cm (centimeter)
1/1,000 (10–3) milli- m mm (millimeter)
1/1,000,000 (10–6) micro- ( (F (microfarad)
1/1,000,000,000 (10–9) nano- n nm (nanometer)
1/1,000,000,000,000 (10–12) pico- p ps (picosecond)
1/1,000,000,000,000,000 (10–15) femto- f frad (femtoradian)
1/1,000,000,000,000,000,000 (10–18) atto- a aT (attotesla)
When will we reach 1 Exa Hash per second? EH/s <---- Eh? Canadian named it.