Γράφω τη διεύθυνση στο μπλοκάκι μου για να μην την ξεχάσω.

Γράφω is the present form of γράφω (to write). In Greek, the present tense can mean either:

• I write
• I am writing

So in this sentence it can naturally mean I’m writing down the address... depending on context. Greek uses the same form for both the simple present and the present continuous.

τη διεύθυνση is in the accusative case because it is the direct object of γράφω.

• η διεύθυνση = the address (nominative)
• τη(ν) διεύθυνση = the address (accusative)

In English, the noun itself usually does not change, but in Greek the article changes to show the noun’s role in the sentence.

Both are possible, but τη διεύθυνση is very common.

The full form of the feminine accusative article is την, but the final -ν is often dropped before certain consonants. Since διεύθυνση starts with δ, many speakers write and say τη διεύθυνση.

So:

• την διεύθυνση = also correct
• τη διεύθυνση = very common and natural

You will see both in real Greek.

στο is a contraction of:

• σε + το = στο

σε can mean in, on, at, or to, depending on context.

So στο μπλοκάκι literally means something like:

• in the notepad
• on the notepad
• more naturally in English here: in/on my notepad

Greek uses σε + article where English may choose different prepositions.

μπλοκάκι is a very common word meaning small pad, notepad, or little notebook.

The ending -άκι is often a diminutive, which can suggest:

• something small
• something familiar or everyday

So μπλοκάκι comes from μπλοκ, but in practice it often just means notepad naturally, without a strong sense of tiny.

In Greek, possessive words like my, your, his/her are often expressed with weak pronouns placed after the noun.

So:

• το μπλοκάκι μου = my notepad
• literally: the notepad of me

This is the normal Greek pattern:

• το σπίτι μου = my house
• η τσάντα σου = your bag

για να means to, so that, or in order to.

It introduces a purpose clause:

• Γράφω τη διεύθυνση... για να μην την ξεχάσω.
• I write down the address so that I won’t forget it.

This is a very common Greek structure for expressing purpose.

Because after να, Greek uses μη(ν) for negation, not δεν.

A helpful rule:

• δεν negates indicative verbs
• μη(ν) negates subjunctive forms and certain other non-indicative structures

Here, ξεχάσω is in a να-clause, so the negative must be μην:

• για να μην την ξεχάσω = so that I don’t forget it

Not για να δεν...

Because after να, Greek often uses a subjunctive form, and here ξεχάσω is the aorist subjunctive of ξεχνάω / ξεχνώ.

This form is used because the speaker means a single complete event:

• to forget it

So:

• να μην την ξεχάσω = so that I won’t forget it

If you used the present-type form instead:

• να μην την ξεχνάω

that would sound more like:

• so that I’m not forgetting it repeatedly
• so that I don’t keep forgetting it

So ξεχάσω is the natural choice here.

την means it, and it refers back to τη διεύθυνση (the address).

Because διεύθυνση is:

• feminine
• singular
• accusative here

the pronoun is also την.

So:

• τη διεύθυνση = the address
• την ξεχάσω = forget it

Because object pronouns in Greek usually come before the verb.

So Greek says:

• την ξεχάσω = literally it forget

This is normal Greek word order for weak object pronouns:

• τον βλέπω = I see him
• την ξέρω = I know her/it
• το γράφω = I write it

Greek often leaves out subject pronouns because the verb ending already shows the person.

Here:

• γράφω = I write / I am writing
• ξεχάσω = I forget in this subjunctive context

So Greek does not need εγώ unless the speaker wants emphasis or contrast.

For example:

• Εγώ γράφω τη διεύθυνση... would mean something more like I’m the one writing the address...

Greek word order is more flexible than English, although some orders sound more neutral than others.

This sentence has a very natural, neutral order:

• Γράφω τη διεύθυνση στο μπλοκάκι μου για να μην την ξεχάσω.

But you could also hear variations like:

• Γράφω στο μπλοκάκι μου τη διεύθυνση...
• Τη διεύθυνση γράφω στο μπλοκάκι μου...

These can shift the emphasis slightly.
Still, the original version is a very normal everyday way to say it.

Modern Greek does not normally use an infinitive the way English does. Instead, it usually uses να + verb.

So where English says:

• to forget
• to write
• to see

Greek usually says:

• να ξεχάσω
• να γράψω
• να δω

That is why Greek says:

• για να μην την ξεχάσω

rather than using a separate infinitive form.

Not always. διεύθυνση can mean:

• address (home, street, email, etc.)
• sometimes direction
• sometimes management/directorship in other contexts

But in this sentence, because of γράφω and the context of writing it down, it clearly means address.