A number a is at least - 3

To determine whether a number "a" is at least -3, you need to compare it with -3.

If "a" is greater than or equal to -3, then it satisfies the condition "a is at least -3".

To visually represent this on a number line, locate -3 on the number line and check whether "a" is to the right of or on the -3 mark. If it is, then "a" is at least -3.

In algebraic terms, you can write the condition as:

a ≥ -3

This inequality states that "a" must be greater than or equal to -3 to satisfy the condition.