Refers to the number that comes after seventy-six and before seventy-eight.

सत्तूर

English Usage: My house number is seventy-seven.

Hindi Usage: मेरे घर का नंबर सत्तूर है।

Can refer to the numeral 7 or a group of seven items.

सात

English Usage: I have seven apples.

Hindi Usage: मेरे पास सात सेब हैं।

Used to describe something that is seventy in quantity or measure.

सत्तत्तर

English Usage: She is seventy years old.

Hindi Usage: वह सत्तत्तर साल की है।

Describes a group size or quantity of seven.

सात

English Usage: He scored seven goals this season.

Hindi Usage: उसने इस सीजन में सात गोल किए।