Prime Numbers

Number Theory Level 1

If A = {Prime numbers less than 20} ,
B = {Whole numbers less than 10 },
then A - B = ?

11,13,17 11,13 11,13,17,19 10,13,17,19,21 11,13,19

1 solution

Young Champ
Feb 11, 2015

A={2,3,5,7,11,13,17,19}

B={0,1,2,3,4,5,6,7,8,9}

A-B={elements of A not present in B}={11,13,17,19}

$B$ actually also includes all negative integers. But since none of those are prime, it doesn't contribute to $A-B$ .

Tijmen Veltman - 6 years, 4 months ago

Actually, whole numbers $\neq$ integers.

The set of whole numbers doesn't include negative integers.

Micah Wood - 6 years, 4 months ago

B should've been natural numbers less than 10

Rifath Rahman - 6 years, 3 months ago