siebzig
seventy
The cardinal number that comes between sixty-nine and seventy-one; the number 70.
Für das Konzert wurden über siebzig Karten verkauft.
Over seventy tickets were sold for the concert.

seventy
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seventy
The cardinal number that comes between sixty-nine and seventy-one; the number 70.
Für das Konzert wurden über siebzig Karten verkauft.
Over seventy tickets were sold for the concert.

The tens numbers from 20 to 90 end in '-zig' in German. Note that 'sieben' is shortened to 'sieb-', similar to how 'sechs' becomes 'sech-' in 'sechzig'.
Das Buch hat siebzig Seiten.
The book has seventy pages.
In compound numbers like 71, German names the ones digit first and then the tens digit: 'einundsiebzig' (seventy-one, literally 'one-and-seventy'). This 'ones before tens' rule applies to all numbers between 21 and 99.
Mein Opa ist dreiundsiebzig Jahre alt.
My grandpa is seventy-three years old.
'Siebzig' can also be used as a noun. 'Die Siebzig' means the age of 70. 'Die Siebziger' (plural) refers to the decade from 1970 to 1979.
Nächstes Jahr feiert meine Mutter ihre Siebzig.
Next year my mother will celebrate her seventieth birthday.
seven
'sieben' and 'siebzig' are different numbers, but they have the same beginning. 'sieben' means 7, and 'siebzig' means 70. When listening, the ending can be important: '-zig' turns a one-digit number into a tens number. Confusing them can quickly make a big difference with money, age, quantities, or addresses.

Vor der Reise hat er siebzig Euro abgehoben.
Before the trip, he withdrew seventy euros.
Für den Termin sind sieben Personen angemeldet.
Seven people have registered for the appointment.