
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given the plane vectors $\overrightarrow {a}$ and $\overrightarrow {b}$, with $|\overrightarrow {a}|=2$, $|\overrightarrow {b}|=1$, and the angle between $\overrightarrow {a}$ and $\overrightarrow {b}$ being 60°, determine the value of the real number $λ$ if $(\overrightarrow {a} + λ\overrightarrow {b}) ⊥ \overrightarrow {b}$.

Present the answer in LaTex format: \boxed{Your answer}
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