Which prefix has the symbol 'da'?

Which prefix has the symbol 'da'?

• A. Deca; da; Ten
• B. Deca; D; Ten
• C. Deka; da; Ten
• D. Mega; M; Million

Answer: (A)

Think in terms of SI prefixes and their symbols. The prefix for ten is deca (also spelled deka in some contexts), and its symbol is da. That means when you attach it to a unit, you’re multiplying by ten, as in decameter meaning ten meters. The correct choice uses the standard spelling Deca with the symbol da and the meaning Ten, which is exactly what this prefix represents. The other options use either the wrong symbol (D isn’t a prefix symbol in SI) or a different prefix-magnitude (Mega with M means a million), so they don’t fit.

Think in terms of SI prefixes and their symbols. The prefix for ten is deca (also spelled deka in some contexts), and its symbol is da. That means when you attach it to a unit, you’re multiplying by ten, as in decameter meaning ten meters. The correct choice uses the standard spelling Deca with the symbol da and the meaning Ten, which is exactly what this prefix represents. The other options use either the wrong symbol (D isn’t a prefix symbol in SI) or a different prefix-magnitude (Mega with M means a million), so they don’t fit.